(Author's Note: I don't know sh*t about later chapters of Mushoko Tensei so it is going to be an Au, though I will try to keep many things from the Original same).
3rd Pov
Universe 3462665###^$%%$#(Mushoko tensei World)
In the vast Multiverse, the Universe 3462665###^$%%$# can be said as a Mid-High World/Universe or at least how it was. Currently, its rank has dropped to Mid-Low World/Universe. How did this Universe drop in Rank? A question no one asks after all how many know about the existence of the Multiverse? How many can travel between worlds/Universes? The majority of People who can travel are at least Galaxy Tier beings and they are strong enough to create their own world so they won't care about a low-rank world such as Universe 3462665###^$%%$#.
This Universe was created by a being called Creator God by the people of this world.
The Creator God, a being at Galaxy Level created this world, he created six dimensions of this universe for different species. They were Dragon World, Demon World, Human World, Beast World, Water World& Sky World. The different species inhabited each world and they were named after the species of the residents of the world.
The Creator God used much of his power in Creating the worlds and his level dropped to a planet level being, he will be having a huge lifespan still died like a mortal. His death started disputes between the different races, though there wasn't a war due to each species having a different world their disputes created a rivalry, and to win the rivalry each race needed strong people, Strong people were respected, and soon the feeling of power, respect corrupted the strong people, they started thinking themselves as the rulers, overlords and superior beings than those who were weaker, a hierarchy of strong prey over weak started and started inner turmoils in the races.
The Creator God had predicted that something like this will definitely happen and so to ensure that each race doesn't become extinct he create Gods who presided over each world.
The Dragon World had Dragon God and the Five Dragon Kings/Generals, Demon World had Demon Gods, the Human world had Human God, Beast World had Beast God, The Water world had Water God and the Sky World had Sky God.
Though the Gods did have disputes they ensured the survival of their own race. Everything was fine or that was how supposed it should have been.
Due to the release of the Negative Energy by Humans a being or Evil entity was born. The Entity usurped the powers of the real Human God and became Human God itself. The being Named himself Hitogami.
The being wanted to destroy the world and get more powerful by the release of the Negative energy that will be caused by the chaos, destruction, and war. However, he wasn't that strong to take on all Gods himself yet during that time so he decided to Manipulate the Strongest God to start a war with all other Gods.
He manipulated the Dragon God and his five Generals on destroying the Demon world, beast world, sky world & Ocean world. Due to the Negative Energy produced by the massacre and destruction of the world, he became a Constellation level being. He was now strong enough to take on the Dragon Gods himself so he started a war with them. Dragon God finally realized how Hitogami manipulated them but it was already late, Hitogami has became too strong by that time for them to kill him.
Hitogami killed all the four Dragon Generals, Dragon God on seeing that he cant kill him teleported his son Orsted to the Human world and used his all powers and lifeforce to trap the Human God in the void a place which even the Creator God feared of. Before his death, he ordered his last serving Dragon King/General, The Demon Dragon God Laplace to find a method to kill Hitogami. Laplace took an oath that he will kill Hitogami or die trying.
The Human God wasn't fully trapped in the void at that time since the spell needed some time before completely trapping him so he used his powers to kill Laplace during his escape to the Human World, the Laplace survived the attack but due to the attack containing some properties of the void, it divided his existence into two parts. The Dragon Half can only use touki and the Demon Half can only use magic.
(Author's Note: I know he was divide by Human God's Apostle not him but I already told you guys that this will be a bit Au since I lack Knowledge of the later chapters so I am making some things Au for my own convenience)
Laplace wasn't just divided into two-piece but his whole existence was divided so all his memories were erased but his oath wasn't. Unfortunately, the Dragon Half only remembered the God part of the oath while his Demon side only remembered the Human part of the oath.
Dragon side of the Laplace misunderstood his oath to become the strongest God so he created many Fighting Techniques and therefore he was named Technique God. He established the Seven world power ranking while being ranked Number 1 officially.
The Demons side of Laplace was in a coma for some time. Before his awakening, there was chaos in the human world. The remaining survivors of Demon, Sky, Water & Beast world took refuge in the human world and they started to fight for the resources. Humans had a home advantage compared to the other species so they started winning over other races, however, some powerful beings of other races became God-ranked beings and Humans and Beastmen came under a truce. People of the Water world were mostly Aquatic creatures so they started living inside the seas without giving any problems to Humans. Unfortunately, Sky people were exterminated in the war.
While Humanity didn't have any problem with other races after this they still raged wars against the Demon kind. Demon Kind didn't have any home advantage and Demon Gods were already dead so they started losing against humanity.
During this time Demon Half of Laplace woke and he just remembered the word Human and didn't remember the God part of the oath so he started killing the Humans and Demons started winning against the Humans. In the end, seven Heroes came together and tried to kill Demon God but despite having some God-ranked individuals they failed in killing him so the last three serving members of the Seven Heroes sealed him.
The Human side won so they chased away Demons from the Central continent to the Demon continent. A continent that was previously part of the Central continent but was divided by the Laplace as he broke the Central Continent into two Halves.
Just like that 500 years passed and nothing of noteworthy happened until a small girl Ariria was born in the Asura Kingdom. At birth, her soul got some powers from the remain of the Creator God and some negative energy which gave her two powers. The Ability to Return by Death and to change the state of anything whether living or not to its state that was 24 hours ago.
After knowing about her powers the King used her. She at first was okay with this but she died and returned at her birth. Her life was repeated, again and again, each time she died due for some reason, to her ability to return by death transmigrated from the point of her death to her birth but unlike Subaru's Return by death her powers couldn't change her destiny, her fate was to die and to repeat her life from her birth.
She started seeing the world as Grey and became emotionless, hr life repeated again, and again until something different happened at her 3536th reboot, the King of the country summoned a hero from another world to kill demons.
The Hero was a Japanese boy named Akhitio, she started spending time with him, her life slowly got back her colors and before she knew it she has already fallen in love with him.
Unfortunately, the world wasn't kind to her, The Hero died he was killed by a demon general who sliced his head from his body in one attack.
When she knew the news it already has been over 24 hours and she failed to resurrect him. Her life lost colors again and the world returned to being grey for her and just like always she died.
She at death thought she will die again? This is nothing new to her but for some reason, she wanted to live this time, she wanted to live with Akhitio so she used her powers at a level that even she didn't know she could, she rebooted the time before even her birth i.e K400, using her power she tried to create a being who wanted to save Akhitio as well and turn the events of the timeline in such a way that Akihito survives but how just being a Mortal she could do that?
Despite her powers, she couldn't create such a being and the world rejected her, the world wanted to remain the timeline that way so she started fighting the world itself, K401, K402, and just like time passed for a few years and she manages to create a time-space gap between the worlds, between her Universe and Akhitio's Universe. She used her powers to summon him but two additional people were dragged, they were Nanoshi Akhitio's Childhood friend and A fatass man who died near Akhitio and his soul traveled the Time-space gap and Took over the body of Rudeus.
The Existence of Rudeus was small but it changed the future and the future started going on an unknown path. The time-space gap teleported Nanoshi and Akhitio at different points of the timeline, in an event known as Mana Calamity Nanoshi was transported into the world.
Rudeus changed the future and due to being a variable and possible cause of Hitogami's Death, Hitogami realized the existence of Rudeus only after Mana Clamity, on seeing his future there was a possibility that Rudeus' Children and Norn's Daughter will kill him so he manipulated Rudeus and became successful as he killed Rudeus' unborn Daughter and Roxy who was pregnant with her. Rudeus became depressed and vowed to kill Hitogami and but he realized he couldn't kill him.
The timeline wasn't the one in which Akhitio can survive so Ariria with her remaining power tried to reboot the timeline again but she only could make a minor change which was for Rudeus to meet Eris. This time Rudeus while researching on Time-Space Gap to find a way to transport Nanoshi back to her own world by mistake created a small gap in the timeline and during his fight with Orsted Alternate future Rudeus met the current Rudeus and revealed about Hitogami and on knowing the true nature of Hitogami he finally surrendered to Orsted and became his subordinate.
Future changed so the Alternate Future Rudeus also disappeared and Rudeus married Eris, Roxy, and Eris. Norn married Ruijerd and Aisha married Ars Geryrat Rudeus one of the sons.
Rudeus constantly improved him and always kept his vigilance against Hitogami and just as that time passed. Eris died at the age of 69 due to Old Age and Rudeus soon two years later died too.
After his death, Rudeus met Hitogami one last time and Hitogami told him that now after his death he will start a fight within his children and GrandChildren but Rudeus said it doesn't matter to him.
Rudeus said he didn't feel any regret this time at his death, he already has died and unlike his previous depressing death, he was surrounded by his Children, Grandchildren, friends, and his family. He already has died so why would he care about living matters? He feels that somehow his family will cope with the situation and believes in them. He also thanked Hitogami that if it wasn't for him he would have stopped becoming more powerful, wouldn't have made the education system better, and didn't have lived his life to the fullest if not for Hitogami.
He said to Hitogami that he doesn't like him but also doesn't hate him either. After saying that he patted Hitogami's shoulder and started walking away from him and like all souls that disappear in the Universe 3462665###^$%%$# as mana after their death he dissipated into mana.
Ariria paid the price for changing the timeline and lost all her powers and was reborn a few years later after Rudeus' death and this time she managed to save Akhitio but unfortunately for him, Akhitio didn't love her as he loved Nanoshi.
It broke her, she wanted his love but he didn't love her so she suicided, she already lost her power to turn the state of a thing into the past but she had the ability to Return by death unknown to her and she traveled to the timeline when the Akhitio was summoned for the first time.
She wanted Akhitio's love so she decided t make him fall in love with her and change the timeline again but this time she didn't want Nanoshi to survive so she used her powers to prevent her transportation but failed, but her usage of powers caused a small ripple in the space-time of the whole Multiverse. Due to that Voice of the world when hit by it she randomly selected a human outside of Tensura Multiverse and granted skills he wanted during at his death.
The man's rebirth will change not only the world of Tensura and Mushoko Tensei's world but the Multiverse as a whole.
This is that man's story who got reborn as Rudeus with Great sage and a few extra perks and change the whole multiverse. It's his journey from a normal Human to the Supreme God.
To be continued...