Chijoku no Seifuku

The protagonist spends his day playing with machines and watching pornography without any purpose. He was asked by a friend who was hospitalized in a car accident with his repair store and live in his condo.
One day, Akemi, who lives in the same apartment, asks him to repair an electrical appliance.

He goes to her room, but out of sheer impulse, he planted a camera. He successfully records Akemi's life, and felt a sense of excitement at his crimes.
Afterwards, he also receives a request from Kasumi, whom he had admired for some time, to repair something, and ended up setting a camera in her room too.

When he returned home to check Kasumi's recording, he saw the girl dressed in obscene underwear and lost in masturbation. The protagonist is shocked by Kasumi's lewd side and to leave the room in order to cool his head, where ran into Akemi.

Akemi has always aroused him with her body, and with lust on the brain, he instinctively raped her. Once he regained his faculties, he blackmails her to keep her quiet.

He went back to his room, and although initially horrified with what he's done. it was the first time he ever felt a woman's body.

So he came up with an idea. Using the illegal footage, he's able to rape Kasumi and other beautiful woman as well.