Aru Sabireta Gakkou no Himitsu

Kanetoki is a new teacher at a desolate school with only two students. But was speechless when his twin students, Riru and Aika, kept provoking him. While waiting in the staff room to scold them, two succubi appear. It turns out that the two students were actually two female succubi who were looking for an excellent cross-breeding partner, which they have chosen Kanetoki-sensei for. The other teachers were put to sleep and Kanetoki is unable to escape.