After dying while protecting his junior colleague at work from a knife attack, Satoru Mikami is reincarnated as a slime in a magical world. As someone who is reincarnated, he gains the Skills "Predator" and "Great Sage". While strolling around, he meets the Storm Dragon Veldora who becomes his friend and names him Rimuru. In return, Rimuru gives the surname Tempest to both of them and agrees to snatch Veldora from his prison so that one day they can permanently break Veldora's prison. The mysterious disappearance of the Storm Dragon results in huge consequences as his presence acted as a sort of buffer zone. Meanwhile, Rimuru starts his adventure by traveling, meeting new people, fighting some of them, and turning them into allies by fighting them.

That Time I Got Reincarnated as a Slime (Tensei Shitara Slime Datta Ken) is a series of web-novels turned light novels by Fuse and illustration by Mitz Vah. This series is adapted to manga by Taiki Kawakami and an anime by Studio 8 bit. It also spawned a Spin-Off Manga Tensei Shitara Slime Datta Ken: Mamono no Kuni no Arukikata (The Ways of Strolling in the Demon Country), which is about Rabbit Girl Flamia exploring Rimuru's country and takes place further in the story.

That Time I Got Reincarnated as a Slimeprovides examples of the following:

Action Girl: Shion, in particular, stands out, being a Rare Female Example of The Big Guy.Actor Allusion: This isn't the first time Tia Ballard voiced a pink-haired oni girl with two horns on her head.Adaptation Expansion: The light novel is fairly bare bones in presentation. For example, the character of Shizue has no speaking linesapart from asking to join the adventurers before succumbing to possession, nor does she actually do anything like torch giant ants to show off her strength. She just joins the party, is silent until meeting Rimuru, gets possessed, beaten and then dies while wishing for him to get revenge on Leon Cromwell for her.The Alliance: Among the various forest races under Rimuru, culminating in a new country

Anatomy of the Soul: Souls are divided into three parts. The astral body that connects it with the physical body, a core that builds a protective shell and finally, inside the core, the nucleic Heart where the ego of a person dwells.The Assimilator: Rimuru grows stronger this way, thanks to his [Predator] skill. Absorbing attacks means he can use them at will, and every strong creature he eats means he grows taller in human form. This is contrasted with the orcs who have the powers, abilities and even characteristics of anything they eat while under the effects of the skill [Starved]. The chances of assimilation are less likely, but when successful end up redistributed to all the orcs. For example, devouring an unlucky lizardmen allows the horde to gain scales and webbed digits, which allows them to move through the marshlands quicker.Author Appeal: The author very clearly has a thing for cute monster girls, including Bizarre Sexual Dimorphism with dragonewts and eventually including hot demon girls when before demons were indicated to be genderless.Autocannibalism: Geld tears off his arms and eats them to recover health before growing them back.Awesomeness Is a Force: Downplayed with King Dwargo who is described by Rimuru as 'exuding an aura of raw power'.Be Careful What You Wish For:The world takes into account the target of the reincarnation's wishes before sending them along. Rimuru's casual and unknowing responses turn him into a slime.Gelmud wants Geld to eat enough monsters so he can evolve into a Demon Lord. Geld proceeds to follow his orders exactly, starting by killing and eating his benefactor. This kickstarts his evolution, just like he wanted.Bishounen Line: How power levels are gauged. When a monster is named, it becomes closer to looking human, while keeping previous traits. This means Rimuru, Treyni, Demon Pillars and other extremely powerful monsters appear as beautiful humans. Veldora subverts this, still looking like a dragon despite how powerful he is and when he actually gains a human form, it's more for convenience than an actual power boost.Bland-Name Product: Before Rimuru dies at the start of the series, he tells his friend to destroy his hard drive. In an anime only end of episode gag we actually get to see him do this, and Rimuru's computer runs on "Mechasoft Doors".Bring My Brown Pants: Outside the Dwarven kingdom, when Rimuru scares a party of human adventurers off, he is informed that a portion of witnesses soiled themselves in the process.Cannot Tell a Lie: Monsters are incapable of lying directly. If they lie, they'll disappear immediately. Lesser ones that are capable of normal sexual reproduction aren't held to this, however. However, when humans get too complacent about trusting monsters they tend to get tricked and screwed over badly: They're still capable of lies by omission or misleading truths. After awhile this idea is seemingly scrapped with the acknowledgement that monsters with a primarily spiritual body can also lie consequence free. So who exactly is bound by this rule?Cardboard Prison: When briefly put in prison for (accidentally) causing a very large public disturbance outside the Dwarf city, Rimuru is put inside a barrel as well as a cell. As slimes in this universe are typically seen as one of the weaker beings and might be able to contain them, Rimuru is no ordinary slime. He gets out of it (and the cell) as soon as he wants to.Characterization Marches OnHinata Sakaguchi is introduced as a high-functioning sociopath who had already murdered her father to collect on his insurance money (though he maybe deserved it) and was considering murdering her mother soon for being a burden. When attacked after being summoned, she brutally murdered her assailants, though once again they weren't exactly sympathetic characters. However, by the time she comes into conflict with Rimuru, she's instead characterized as a slightly odd girl who is only trying her best to save people from dangerous monsters.When Leon Cromwell has his first fight, it's made clear that when cutting loose he doesn't really care if his own men get caught in the crossfire. They understand this and don't begrudge him at all. However, much later on suddenly he can't go all out for fear of getting his men hurt.Chuck Cunningham Syndrome: After the Templar attack on Tempest the author seems to have tired of Shion and most of the onis, though Benimaru actually gets morespotlight for once. The demons Diablo, Testarossa, Carrera and Ultima generally take up the narrative slack plus some emphasis on the labyrinth bosses.Complete Immortality: When killed, demons eventually revive in the underworld. Presumably the same for other spirits. However, most likely, if eaten by someone like Rimuru they probably don't come back.Covers Always Lie: Some posters show Rimuru, in human form, alongside Shizu. Shizu later dies, and Rimuru doesn't get a human form until he absorbs her following her death.Cute Monster Girl: Humanoid monster races named by Rimuru tend to become much more human looking, though not always. The small, dopey goblins turn into buff goblin men and cute goblin girls, for the most part, while the ogres shrink in size and become less wild looking. It doesn't always happen, but even several lizardmen women take or can assume a basically human form, depending on whether you're reading the web novel or the light novel/manga.Dark Is Not Evil:According to Rimuru, demons aren't actually evil even though they're basically darkness spirits. In practice, however, they tend to be sadistic monsters. They aregenuinely loyal to summoners that they respect, however.Most of the monster races are shown to not be so different from the other races and can come off as friendly. At one point the idea is floated of reclassifying them as demihumans instead but the idea is dropped. It still implies that (humanoid) monster and demihuman are interchangeable but one is basically just a slur.Death Is Cheap: Resurrection magic is supposed to be extremely difficult and doesn't even work right, but even so dead characters have an odd way of coming back to life just fine up to and including three quarters of a million enemy soldiers.Defeat Means Friendship: Most of Rimuru's (incidental) way of gaining allies follows the same pattern: Some people pick a fight with Rimuru; Rimuru shows his skill and, if possible, talks to them; Rimuru gains allies. Subverted with the Goblin Tribe because they know fighting is futile, thus surrender as soon as they meet Rimuru and Veldora who can't fight at all but is a very reasonable guy.Demon Lords and ArchdevilsDemon lords are individuals from any race that consumed human souls to trigger an evolution into a special almost godlike being. They aren't necessarily demons and, in fact, only one of the ten at the start of the story actually is one.Actual demons are ranked from lesser to greater to arch to dukes. Lesser demons are reasonably strong, but both they and greaters are basically fodder. Archdemons are rare, powerful monsters and demon dukes are nearly unheard of. The latter are at the same level as demon lords.Don't Try This at Home: A disclaimer reading "Never attempt this" pops up as we see Temura dump his computer (plugged in, no less) into the bathtub, as Rimuru told him to do before dying.Driven to Villainy: The Orc Lord states he had no choice. Either consume the other races or let his race starve to death.Dumb Muscle: Shion is a strong swordswoman but she tends to use her sword more than her brain.Easily Forgiven: Several characters such as Bester and Gabiru, should have been either given a Karmic Death, or at least been thrown in prison. However, Rimuru allows them to help out in the village later on. Even the orcs, who until their master was defeated by Rimuru, are shown leniency that surprises everyone, including them.Egopolis: Defied by Rimuru, who objects to the capital city of the Jura Forest Alliance being called 'Rimuru', but played straight when everyone calls it that anyway.Evolutionary Levels: Every species has higher forms they can evolve into. Mostly the change is linear but there can be variants sometimes.Goblins evolve into Hobgoblins (for the males) and Goblinas (for the females).Humans after overcoming several odds can evolve into Sages, who in turn evolve into Saints.Rimuru himself evolves after some time into a Demon Slime when awakening into a True Demon Lord and later he becomes an Ultimate Slime, reaching the pinnacle of his species.Ogres can evolve into Oni if they attain enough power and can further evolve into Fair Onis or Evil Onis.Evolution Power-Up: All lifeforms in the world are able to do this, acquiring more power the more they evolve.Exact Words:Gelmud tells Geld to evolve into a Demon Lord already. Geld fulfills his request by killing and eating him, prompting his evolution.When the elf does her fortune telling for Rimuru, she shows him Shizue as "the one destined to be with you". She literally gets eaten by Rimuru, offering him his humanoid form.Explain, Explain... Oh, Crap!: When Gabiru arrives in the village, he tries to convince Rimuru that the goblin village should become his subordinates because they are so weak. However as he is explaining this he starts to notice that his audience is a hobgoblin, a slime and a group of evolved ogres, and not a weakling goblin in sight.Generic Doomsday Villain: Kagurazaka Yuukidoesn't really have any kind of decent motivation. He just wants to destroy the world because he wants to destroy the world. There's a vague acknowledgement that he maybe had a tough childhood or something but even the characters don't believe that this makes any kind of real sense. There's actually some setup for him being more than this during the middle part of the story, but in the end it's all scrapped and he's just all MWUAHAHA I will burn everything!Genre Savvy: Zig-zagged by Rimuru. He expects the Lethal Chef trope. On the other hand, he can't predict that naming stronger monsters will be more difficult than naming weaker ones.Harem Genre: Hilariously subverted, as while Rimuru identifies as male, admits that he would want to finally give up his "virgin" status, is very much an admirer of the womanly form, and there's no shortage of interested females, his "little brother" no longer exists.Though he does admit even that with his shape changing ability, that is entirely by choice.Honour Before Reason: Benimaru in his first appearance where he fights against Rimuru even after he realizes the gap between their respective abilities. At this point, he's one of six ogres still alive after the orcs slaughtered his village as well as their acting leader and should be prioritizing the safety of his followers over recklessly endangering them fighting a foe he assumes is responsible for leading the orcs, especially after said foe incapacitated three of them without using anywhere near his full strength. Luckily, Rimuru's an understanding chap.Humans Advance Swiftly: Most monsters have Telepathy so don't use maps or writing and can't pass as much knowledge onto their children so humans are the most advanced civilizationHumans Are Average: Humans appear to be normal humans, only treated differently by 'monsters' since adventurers kill them.Human Resources: The Summons, who are yanked from other worlds by many nations and powers of this world more-or-less on an industrial basis for the slim chance of producing a Hero-level warrior that might be used against monsters or rival powers. Note that the Summons who fail to develop into heroes usually die within several years as their bodies cannot stand the enormous level of mana acquired in the process.Human Sacrifice: Rimuru needed to kill more 10000 and devour their souls to evolve into a True Demon Lord. He did this by killing the invading army of Falmas that numbered 15000Humble Hero: Rimuru wisely presents a humble front to everyone he meets, although he makes sure people understand he is a ruler of monsters. This gets him criticized by the Dwarven King, who warns him of the consequences of making himself to humble as king of a nation.I Did What I Had to Do: The Orc Lord admits he was aware that Gelmud was using him in an Evil Plan, but tells Rimuru he didn't have a choice. His people were dying from starvation, and he couldn't save them any other way.Immortal Procreation Clause: Monsters and humans that live longer than humans tend to have significantly lower fertility. Demon lords in particular turn out to be sterile. Several races like elves and oni reproduce very slowly not just because of biological limitations but also social ones, which keeps their populations barely at the level of sustainability.Interspecies Romance: Several humanoids develop crushes on other races, such as Soka having a thing for Souei or Garm being interested in Shuna and getting very confused around Rimuru.Large Ham: Veldora shouts often when he speaks with Rimuru.Level Grinding: An unintentional example. While lost in the first cave Rimuru tested his own skills and with the help of the Great Sage skill evolved combative techniques to deal with the dangerous monsters. After slaying them he used his Predator Skill to absorb them, bolstering his physical and magical strength as well as gaining new skills to be analyzed and experimented with. Apparently this went on for weeks and by the time he finally got out of the cave he was one of the most powerful beings in Jura Forest.Loads and Loads of Races: More or less standard Medieval European Fantasy set with some additions, which seems to be inspired by the Monster Quest.Lethal Chef: The nicest thing you could say about Shion's cooking. So lethal in fact, Gobta gets poison resistance just by eating a spoonful of her food.Meaningful Rename: If a demon/monster is named by a strong individual, he/she gains some power from the name but it also means the giver has to give up part of their magical power (though luckily, magical power can regenerate with time). That's why monster parents don't name their kids.Medieval Stasis: Enforced by angels who descend every 500 years in massive armies that destroy any civilization that exceeds a certain level of development. Dwargo used to be the only survivor of such an assault before Tempest came along.Monster Town: The Goblin Village. Under Rimuru's leadership and the help of a growing number of advisors, more and more races join the expanding village until it becomes an outright Monster Nation known as Tempest.No Biological Sex:Demons don't appear to actually have fixed genders. Guy can switch between a male and a female form as he pleases, though he defaults to male. Diablo seems to have no sex at all, though 'he' is beautiful either way. Carrera, Testarossa and Ultima are either all female or simply choose to look that way.Slimes by default don't have any fixed genders or sexes from both not needing sexual reproduction and as a rule just plain not sentient enough to acknowledge such things.Odd Friendship: A slime and a dragon? Who would have thought it?Older Than They Look:Rigurd was old enough to be a frail, old man, but after being named by Rimuru becomes a huge mass of muscle who looks to be in his 30s.Shizu is in her 70s based on her death in the Tokyo Fire Bombing but she still looks 17. When she dies, her hair whitens and her skin ages to reflect her true age.Rimuru's human form looks like a young teenager at most but mentally he's nearly 40.Most demons look like they're in their 20s-early 30s but have lived over a hundred years. Milim is an excellent example as she looks and acts like she's in her early teens but is stated to be the strongest and oldest of the Demon Lords.Only a Flesh Wound: Rimuru receives "fatal" wounds with an alarming frequency, but since he's actually a slime they have no real effect on him since he has both the Pain Nullification and Self-Regeneration skills on hand. Nothing short of total bodily destruction would probably stop him.Our Demons Are Different: They were originally called Dark element spirits and are spiritual lifeforms that dwell in the underworld. They only appear in the material world if summoned and quickly disappear if not given a suitable physical vessel.Our Goblins Are Different: The goblin tribe Rimuru originally meets are short and weak physically like children, though they are clever and skilled enough to quickly erect fortifications as well as use basic weapons like spears or bows. After he names them, they transform into Hobgoblins and Goblinas for male and female respectively, who essentially resemble green-skinned adult humans with developed canines and pointy ears save for the actual children. Except for Gobta, who still appears the same ("My growth was more of a spiritual type!). Personality-wise, however, they're practically no different from tribal humans who have no issues with coexisting with former enemies in peace.Petting Zoo People: The Beastmen, who have several species and varying degrees of anthropomorphism from this and Little Bit Beastly.Plant Person: Dryads! Very rare and the 'C.E.O' of the Great Forest. Treants are also mentioned.Playing with Fire: Shizue specializes in this, to the extent people are scared of her. Rimuru starts to do this after he consumes her, and Ifrit, the fire spirit possessing her.Prophecy Twist: Rimuru has his fortune of a woman he is destined to be with. He assumes that this means lovers. Said woman actually dies shortly after he meets her, but her dying wish is that he assimilate her.Reincarnation: They're rare but have enough presence that people know what the deal is with them (i.e. they have power, be it skills or resistances, based on the conditions they died in and their choices). Rimuru and Shizue are known examples. People who are reincarnated are given a choice of what kind of power is blessed to them by the "Voice of The World" in addition to a blessing of power based on the conditions they died in. Most of them tend to retain their original form, however, which is why Rimuru's accidentalrebirth as a slime is noted to be rather odd.Satellite Love Interest: Many characters exist for literally no other reason than to be the love interest to one of the side characters, such as Momiji the tengu fangirling Benimaru or Souka the Dragonewt crushing on Souei, though at least she also has a brother to bounce off.Seven Heavenly Virtues: Represented by the virtue series of ultimate skills. Each of them is named together with an archangel. Collecting all skills of this series would allow its user to unseal the Mind of the AngelsJustice King Michael wielded by Emperor Rudra, later claimed by VeldaWisdom King Raphael wielded by RimuruCovenant(Faith) King Uriel wielded by RimuruPurity King Metatron wielded by Leon CromwellPatience King Gabriel wielded by VelzadoHope King Sariel wielded by Cloe O'BellCharity King Raguel wielded by VelgryndSeven Deadly Sins: Represented by the Sin Series of the ultimate skills. Each of them is named together with an Archdemon. Collecting all skills of this series would allow its user to unseal the evolution tree of the DemonsLustful King Asmodeus used by Ruminas ValentineGluttonous King Beelzebub used by Rimuru TempestGreedy King Mammon used by Kagurazaka YuukiSlothful King Belphegor used by DinoWrathful King Satan used by Milim NavaEnvious King Leviathan used by Ice Dragon VelzadoPrideful King Lucifer used by Guy CrimsonShout-Out:The design and animation of Ranga's father brings Kiba to mind.In Episode 6, Rimuru tries to break the ice with the adventurers by saying "I'm not a bad slime!", which is a line friendly slimes in Dragon Quest tend to say as a greeting. Shizue cough-laughs, and later reveals she knows the line is from a video game thanks to another reincarnated person she knows.Showy Invincible Hero: Tempest rarely struggles and essentially never loses. Rimuru himself has only lost a single fight.Slime Girl: Played With. Rimuru is a Slime, though not a girl, owing to his lack of sex in his usual form. He has a human form which looks more or less female, being based on Shizu's body, though it lacks attributessimilarly to his slime form. Rimuru himself identifies as male and is often frustrated when taken for a girl.So Last Season: The story can go through this quickly as a result of Rimuru and his followers gaining more strength from foes either joining their cause or being absorbed to add their power to Rimuru's. As an example, a lesser demon puts up an okay fight against Rimuru, then he summons a greater demon to inhabit a golem. Next is an archdemon, at which point greater demons are total loser small fries. Then archdemons become fodder to hype up devil dukes, which are in turn overshadowed by devil lords.Spoiler Opening: The anime's OP has a number of minor spoilers here and there with the most notable one being that Rimuru will gain the ability to shift in and out of a human form.Stupid Sexy Flanders: Garm keeps getting confused by Rimuru's androgynous form; it doesn't help Rimuru often gets dressed like a girl.Stunned Silence: All the Lizardmen and Rimuru have this when Gobta defeats their leader Gabiru in a single kick. The lizardmen can't believe Gabiru was defeated so quickly, while Rimuru can't believe Gobta actually won.Later, Souei slaughters the orcs in the caves of the Lizardmen so impressively and elegantly that Gabiru's sister is gawking in shock. Her father (the chieftain) and his attendants have the same reaction when Souei puts the last orc attempting to ambush them into a You Are Already Dead situation with razor wire, causing her to hang a lampshade on this trope.Suspiciously Specific Denial: Veldora certainly doesn't find the heroine who sealed him away attractive, nope. He doesn't think she has lovely hair or that her pale skin is lovely or that she has a personality that he likes.The Thing That Goes "Doink!": Rimuru's hot spring bathhouse features a shishi-odoshi for that touch of traditional Japan.Took a Level in Badass:Rimuru has an ability called Predator which enables him to eat any material and make it part of his power.If a demon/monster is named by a strong individual, he/she gains more power.Undying Loyalty: A combination of Rimuru's kindness and sheer power inspires this in a lot of the monsters living in his nation. It probably helps that most of them are monsters he personally named.Villainous Breakdown: Gelmund sees Rimuru's small force completely destroyingthe Orc army, and starts panicking over how his plans are spiralling completely out of control. He clearly wasn't expecting a monster of Rimuru's caliber to suddenly show up and start giving power to the Forest of Jura's natives, as said reinforcements' strength are completely out of left field as far as he is concerned.Wham Episode: Episode 8, where Shizu dies, despite being set up as a Rimuru's partner. To be fair, they do wind-up together forever.The Worf Effect:Characters are often compared to a vague 'Demon Lord' or 'Awakened/True Demon Lord' level and for mooks it's always the vague A rank or above A rank metric. This doesn't serve as very good hype since one of the first demon lords seen, Clayman, goes down like a complete chump since Rimuru has already reached that level of power when he fought him while "True Demon Lord" can range from small fry like Ruminas to literal gods depending on how much power they gained before their ascension and how much they kept building it up afterwards.This actually pointed out in the light novel that anyone who reaches a certain level of power can proclaim themselves a Demon Lord, but in order to be officially recognized as such they need the backing of two existing Lords or be ruthlessly crushed by the established ones. So many such self-proclaimed Lords have come into existence that at least one human kingdom doesn't even consider it a big deal. Milim herself notes Rimuru had already surpassed the minimum power requirement to become a Demon Lord just days after fighting and absorbing the Orc Disaster. A similar case occurs with the "Ten Great Demon Lords" as only four of them were technically True Demon Lords (Guy, Millim, Ramiris, Dagruel), with the rest either possessing similar levels of power (Dino), had vast armies and resources to bolster their (comparatively) weaker strength (Ruminas and Leon), or were just legitimately weaker in both power and resources, not even possessing Ultimate Skills, but stayed on due to influence and manipulativeness (Clayman, Karion, Frey). The latter two even stepped down after Rimuru defeated Clayman since they realized they couldn't match up to the rest.Younger Than They Look: Rimuru looks like a 16/17 old in his latest human form in the light novel but it has only been 3 years since his reincarnation.Your Days Are Numbered: Once a Summon (a person yanked from the different world by magic) fails to develop a skill that allows them to deal with the enormous level of mana acquired during the ritual — which is a common, and even a normal occurence, — their bodies fail within several years.

Alternative Title(s): Tensei Shitara Slime Datta Ken, That Time I Got Reincarnated As A Slime