Danji is genderless
Danji is absolutely insane, they do not hold a personality for very long.
The tail is NOT sentient. But due to Danji's very unstable personalities they act the tail out as a separate personality. Like a puppeteer who believes that the puppet is alive.
The eyes on the tail are fully functioning, and Danji can see out of them.
The legs on the tail are very strong and can even attach Danji to a wall and hold the full body weight suspended.
Danji has a taste for mushrooms, specifically amathia cap. Which is probably a cause of their insanity.
Danji does not have a specie. This is purely a delusion of their true self.
If you have any questions feel free to ask :D