Nonhumans, demons, degenerate inclinations, cannibalism.
Here is the furthest from BL—
Because of his perverted fetishes, we find Makoto, a so called deviant who has always been struggling alone. One day, he finds the “Book of Demon Summoning” and conjures hesitantly a spell, summoning, that way, a demon. Thereupon, a majestic beautiful creature makes an appearance, the one with a silky tongue, the Prince of the Underworld, “J”. In exchange for Makoto’s life, J can make Makoto’s wishes come true and be reborn as a demon, but—!?