Mister Mistress Series by Rize Shinba

What do you do with a demon incubus feeding off your wet dreams? Fujimaru is your typical pubescent teenage boy - horny and girl-crazed. Like many boys his age, he enjoys spending 'alone time' in the bathroom with erotic magazines, doing... you know. Unlike many boys his age, Fujimaru has a demon incubus, Rei, lurking about his house Rei wants nothing more than to feed off of Fujimaru's perverted mind

With Rei as his teacher, there is no end to the constant sexual harassment he is subjected to at home and at school. But after finding out that all he has to do is refuse Rei to erase him from his life, will this mark the end of being constantly sexually harassed by another male?