What type of demon is Yomi?

Just asking, just in case anybody had any ideas of their own they would like to share, o knows of any exclusive information not dato in the Anime o manga.

It’s for a fan fiction I'm Scrivere and he's a character, and since I like to be thorough with my characters this information would help me out a lot. I am currently unfamiliar with any fandom concerning him, if there is any, so I guess I'm asking about that as well. I guess the real domanda here is, what type of demon would te like Yomi to be, o can accept him as in a fan fiction?

(*Note, there will be romance, I think, but not with Yoko XD)