Murata-sensei to Tamura-chan

Mr. Murata, a high school teacher, has always been good at everything he does. But now he has a problem. He is being bullied by his student, erotically. She is Tamura, the center of the class. She uses every possible means to threaten him, shake him, catch him, gather evidence, and then threaten him again. The other day, she took a picture of him in a compromising position. And today, in the infirmary, Tamura said, "Strip naked and get down on the floor, won't you?" Then she pulls out a small pink toy. "Can you open up your asshole and show me?" The problem is, there's a part of him that doesn't mind, that can't resist the immoral sensuality…

(Source: Kuro Mitou, translated)