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.
I think it's probably because 
I've never been in love...
أظنّ الأمر هو أنّني لم أقع 
...في الحبّ من قبل
Das liegt sicher daran,
dass ich noch nie verliebt war.
Creo que es porque nunca
he estado enamorada…
Creo que es porque nunca
he estado enamorada…
C’est plutôt que je n’ai jamais eu
de petit copain…
Penso sia perché non mi sono mai innamorata.
Imagino que seja assim 
porque nunca me apaixonei.
Наверное, потому, что я ещё
никогда не влюблялась...