Sensei! Shite Ageru

Inaba Yoshiharu is the new teacher who takes care of the student dormitory.

The fresh teacher is popular, and actually a perverted man who loves younger girls.
He isn't taking any specific actions though, since he is satisfied with his current teacher-life.

One day, a quiet but distinctive girl, Akiho, approaches him, and they start to have a sexual relationship.
Although he was perplexed, Yoshiharu couldn't defy the sexual pleasure he felt for the first time.
The next day, Yukino, a serious student who acts as the dormitory leader, visits Yoshiharu's room, demanding a relationship similar to Akiho's.

From that day on, the strange relationship with the devilish racking Akiho, and the always spoiling Yukino began.

[translation from Getchu]