Sensei Shokushin shite Kudasai!

A construction worker, Saeki is very interested in anything that has to do with sexual pleasure. When his coworker tells him about the red-light district where a man plays with his butt, he instantly denies the sexual hobby but cannot resist trying it later at his home. He tries to find the erogenous zone and happens to push a buttery deeper. He cannot take out the battery. So, he meets Dr. Kirishima, a handsome male gastroenterologist with long hair, for the treatment and dares to ask the whereabouts of his prostate. The doctor technically indicates the place. But the feelings are so good for Saeki that, to his surprise, he asks Kirishima, "Could you put your dick in...?"

(Source: Takeshobo)