Tooru documents his irrepressible erotic fantasies in his "Fetish Diary". Writing in it both helps him repress his insatiable lust and serves as a way to get himself off in a way other than mere masturbation.

Then, one day Tooru forgets his Diary in the classroom so he hurries back to pick it up, but what he finds is his classmate Ootori Chikage masturbating while reading his diary.