サディスティックりとる

Takahata Kousuke, a rookie teacher with some very hardcore otaku hobbies,
ends up having his biggest, most embarrassing secret—tied directly to those hobbies—discovered by none other than his two favorite students.

From that day on, the relationship between teacher and students flips completely.
No longer just a teacher, Kousuke becomes their slave, and the two girls, fueled by their youth and competitive streaks, start pushing him to his limits, each trying to outdo the other.

And so begins the protagonist’s life of suffering, caught in the crossfire of their rivalry.

[Translated from the official website]