Takahashi Tetsuo, a biology teacher at Shizaki High School, has been fascinated with "demi-humans," beings with characteristics that differ just slightly from humans, since he was in college. He wishes he could have a chance to talk with one, but since the demi-human population is fairly low, he's never even met one. But then the school gains a new math teacher, Satou Sakie... who happens to be a succubus.
or I'm making the most of my youth, 
or some other old man's thought!
،أو أنّي أعيش أفضل ما في شبابي
 !أو أفكار أخرى تراود العجائز
o que aprovecho mi juventud
o alguna cosa de viejos.
o que aprovecho mi juventud
o alguna cosa de viejos.
que eu tenho aproveitado bem
 ou qualquer outra coisa de velho!
мол, хорошо быть молодой,
или вот он, цвет юности!