These are the unfamiliar words frequently used in the story. I have written it down to avoid conflicts and confusion.

Chan/Kun/San/Sama/Shi: These words are originated in japan because the setting itself is from japan therefore, I used these words to stir a little Japanese culture. It may sound weabby but yeah.

What is the difference between san, sama, kun and chan?

In Japan, when talking about other people, one uses honorific titles after their name. The most common title is san (さん). It means all of "Mr", "Mrs", "Miss", and "Ms." Mr Tanaka is referred to as Tanaka-san, as is Mrs Tanaka, and their unmarried daughter. Other common titles include sama (様), a more polite version of san, sensei (先生), for teachers, kun and chan. These titles also come after the name.

Correct use of titles is very important in Japan. Calling somebody by just their name, without adding a title, is a form of bad manners, called yobisute (呼び捨て).

Although titles are usually added to people's names, there are some exceptions. They are not used when talking about a family member, or another member of one's "in-group", to someone from outside the group. At work, Ms. Shimizu calls her boss "Tanaka san" when she talks to him, or about him to other people. But when she talks to a customer from outside their company, she calls him just "Tanaka".

San

San (さん) is the most common honorific title. San is similar to "Mr", "Ms.", "Mrs", and so on. There is no kanji form for san, it's written in hiragana.

San may also be used with a characteristic of a person. A bookseller might be hon'ya-san (本屋さん), "Mr. Bookseller". A foreigner might be referred to as gaijin-san (外人さん).

San is also used when talking about entities such as companies. For example, the offices or shop of a company called Kojima denki might be referred to as Kojima Denki-san by another nearby company. This may be seen on the small maps often used in phone books and business cards in Japan, where the names of surrounding companies are written using san.

San is also applied to some kinds of foods. For example, fish used for cooking are sometimes referred to as sakana-san (魚さん).

Both san and its more formal equivalent, sama, imply familiarity. In formal speech or writing, the title shi may be preferred.

Kun

Kun (君) is informal and mostly used for males, such as boys or juniors at work. It is used by superiors to inferiors, by males of the same age and status to each other, and in addressing male children. In business settings junior women may also be addressed as kun by superiors.

Schoolteachers typically address male students using kun, while female students are addressed as san or chan.

In the Diet of Japan, diet members and ministers are called kun by the chairpersons. For example, Junichiro Koizumi is called Koizumi Jun'ichirō kun. However, when Takako Doi, a woman, was the chairperson of the lower house, she used the san title.

Chan

Schwarzenegger AKA Shuwa-chan

Chan (ちゃん) is a form of san used to refer to children and female family members, close friends and lovers. The change from san to chan is a kind of "baby talk" in Japanese where "sh" sounds are turned into "ch" sounds, such as chitchai for chiisai, "small".

Chan is also used for adults who are considered to be kawaii (cute or loveable). For example, Arnold Schwarzenegger gained the nickname Shuwa-chan (シュワちゃん).

Chan is sometimes applied to male children if the name does not fit with the kun suffix. For example, a boy called Tetsuya may be nicknamed Tetchan rather than Tekkun for reasons more to do with phonetics than anything else.

Although it is usually said that honorifics are not applied to oneself, some women refer to themselves in the third person using chan. For example, a young woman named Maki might call herself Maki-chan rather than using a first person pronoun like watashi. Chan is also used for pets and animals, such as usagi-chan.

In the same way that chan is a version of san, there is also chama (ちゃま) from sama. Other variations of chan include chin (ちん), and tan (たん).

Senpai and Kōhai

Senpai (先輩) is used by students to refer to or address senior students in an academic or other learning environment, or in athletics and sports clubs, and also in business settings to refer to those in more senior positions. Kōhai (後輩) is the reverse of this. It is used to refer to or address juniors.

Sensei (先生) is used to refer to or address teachers, doctors, lawyers, politicians, or other authority figures. It is also used to show respect to someone who has achieved a certain level of mastery in some skill. It is used by fans of novelists, musicians, and artists. For example, Japanese manga fans refer to manga artist Rumiko Takahashi as Takahashi-sensei.

Sama (様) is the formal version of san. It's used in addressing persons higher in rank than oneself, and in commercial and business settings to address and refer to customers. It also forms parts of set phrases such as o-kyaku-sama (customer) or o-machidō-sama ("I am sorry to keep you waiting"). Sama also follows the addressee's name on postal packages and letters.

Sama is also often used for people considered to have some high ability or be particularly attractive. At the peak of his popularity, Leonardo DiCaprio gained the nickname Leo-sama in Japan.

Sama is also occasionally used about oneself, as in the arrogant male pronoun ore-sama, "my esteemed self", meaning "I". However, this is not common outside fiction or humour.

Shi (氏) is used in formal writing, and sometimes in very polite speech, for referring to a person who is unfamiliar to the speaker, typically a person who the speaker has never met. For example, the shi title is common in the speech of newsreaders. It is preferred in legal documents, academic journals, and certain other formal written styles because of the familiarity which san or sama imply. Once a person's name has been used with shi, the person can be referred to with shi alone, without the name, as long as there is only one person being referred to.

^I don't really know if this is allowed. But I borrowed the meaning somewhere in sites <>

Space: I used this word in my story often.

"Space" is a word for another dimension, a ghostly world. I got this word from Parallel Universe which they often call it Space in some ways. But let's just call it Another World?

Underworld/Netherworld: It looks different but they are just the same in this story.

"Underworld/Netherworld" is a world for Demons and Death Gods. It's very different from Hell since Hell is a very dominant place for Devils.

Heaven Realm: An angelic home for Gods and Angels.

Nephilim: Half-Human and Half Angel.

Cambion: Half-Human and Half-Demon.

For Future words, I'll update this thing eventually. ~ Thank you for reading!