This is about a guy who gets his nipples molested on a train going to work one day who then goes back to the same spot day after day to enjoy it like a tsundere. (Part 2 is linked in Extra section below.)

⚠Warning: "Chikan is sexual harassment or other obscene acts conducted against the victim's will, or a person who commits such an act. The term is frequently used to describe men who take advantage of the crowded conditions on the public transit systems."