Rie notices her usually talkative friend Yuuko begins to have difficulty talking and has become very quiet. When she stops showing up at school, Rie visits her house. No one answers the doorbell so she decides to go around the back of the house, and finds Yuuko's parents frantically squishing and throwing salt at the slugs that are everywhere.
Yuuko's mother leads Rie to Yuuko's room where she is sitting in bed with a face mask on. Yuuko's mother mentions that the doctor only found Yuuko's mental health to be weak. When she asks to look into Yuuko's mouth, Yuuko refuses.
Rie leaves Yuuko's home and remembers the only other time she had seen her friend so scared. It was in elementary school when some of her friends had come over to play at her house, and one of them tried to scare her with one of the slugs from her backyard, one of Yuuko's greatest fears.
The next day Rie returns to find Yuuko's mother panicked, and sees that Yuuko's tongue has turned into a slug. Rie runs away and never returns to that house. She talks about hearing the lengths Yuuko and her parents went through to get rid of it.
They try cutting off her tongue, but it grew back. Filling her mouth up with salt only made her spit it out. Unable to eat, Yuuko becomes very sickly, and her parents decide to bury Yuuko in a bathtub of salt. She does not resurface, and her parents reach in to grab her but they grab only her clothes. Yuuko seemingly vanished. They find her head in the tub, her body shrunk to a tiny size because of the salt. However, the slug emerges from Yuuko's mouth still alive, and crawls away, her head still attached almost like a snail's shell.