This story makes no reference to the two previous stories in the volume.
Oshiri has been having vivid dreams of finding someone lurking in his house: a strange boy who looks exactly like him and claims to be the "real" Toru Oshikiri. He attributes the dreams to being spooked by living alone in a large old mansion (his parents are always abroad on business.) Oshikiri decides he needs a girlfriend to keep him company.
Oshikiri has to go back after class to pick up his muffler, and finds Satomi, a classmate who spends her time after school painting by herself. He thinks Satomi's pretty enough to be his girlfriend, but when he tries to chat to her, she brushes him off. She doesn't want friends at school because she has three pen pals and that's enough for her. She says that it would be awkward to be seen walking around with him. Oshikiri thinks Satomi is insulting his height, and leaves. When Satomi gets home, she receives letters from two of her pen pals, Yuuko and Miki. Yuuko's letter mentions that she is now in touch with Miki and the third pen pal, Chiharu.
A few days later, Satomi catches up to Oshikiri at school. She apologises for the misunderstanding and says she was being critical of herself, not him. She had mentioned in her letters that she spoke to Oshikiri, and now her pen pals are angry with her - they think she was lying about not having friends at school. Oshikiri tries to suggest that she stop writing to them. After school, Satomi smudges her own self-portrait and insists that Oshikiri sit for her to paint him. Satomi invites Oshikiri to her house but finds that Chiharu wrote back to her. It's an abusive note in block type, cursing at Satomi for making a friend and telling her to "go die." Oshikiri tells Satomi not to write to the girls any more; but she screams at him and orders him out of the house so that she can write to Chiharu. Oshikiri again forgets his muffler and goes back to Satomi's house for it, but bumps into her as she's leaving the house. She drops a letter and Oshikiri sees that it's addressed to herself with no stamp on it.
The following day, Oshikiri sits again for Satomi to paint him. He says he knows that she sent the abusive letters to herself. He believes she was so lonely that she made up imaginary friends, but came to believe that they were real and expected them to be jealous that she made a friend at school. Satomi denies this and is angry that he would think it. She leaves in a rage. Thereafter, she doesn't come back to school. Oshikiri decides that he should go over to her house to give back her painting supplies. When he arrives, Satomi is beside herself with fear and hasn't slept for several days. Her pen pals have continued to send abusive letters and are now threatening to kill her, and she believes they're really going to do it. At this point, Satomi screams and picks up a knife, shouting for her "friends" to stay away from her. Oshikiri tells her there's no one there. Satomi slashes her face and fatally stabs herself in the stomach, screaming the names of Miki, Yuuko and Chiharu.
Oshikiri runs back to his house. He is shaken that Satomi's delusions were so strong it ultimately killed her. He decides not to go to the police; with no other witnesses, Oshikiri would be suspected of murdering Satomi. No one knows that he was ever at her house, so as long as he doesn't say anything, he won't be suspected. That night, Oshikiri hears strange noises in his house again. When he goes investigating, he finds a letter addressed to him, next to the portrait that Satomi had painted of him. The letter accuses him of killing Satomi and says that he left "evidence", his muffler, behind. Oshikiri realizes that the letter is in his own handwriting and signed with his own initials, "T.O."