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A male demon believed to lie on sleeping persons and to have sexual intercourse with sleeping women. It's common to see these demons go after both women and men in anime and particularly BL works, or have a feminine variant acting in the role of a succubus. There are cases where futanari demon girls will act in a similar manner to incubi, but those are counted as succubi for sake of gender.
Incubi are genrally similar in appearance to other demon boys, with horns and demon tails being the most common physical traits. Common depictions of incubi range from "classic demon" (nude, sharp teeth, goblin-like facial features), similar to romantic vampires (long hair, cape, cravat), or leaning more towards succubi (revealing clothes, pubic tattoo).
Notable Incubi
See also
This tag implicates demon_boy (learn more).