A girl named Sui has an unusual disease that causes pain in her eyes whenever she sees light. She has to be locked in a pitch black shed that has no light in it. A boy named Biki helps Sui by removing bandages, giving her food, and just talking to her. Biki's mother is worried about him getting the illness, so she tells him not to stay as long as he normally would with Sui. One day while Biki is talking to her, she tells him why she has that illness: There are Mushi in her eyes. Biki continues to take care of her until one night when he is reading by a candle, a strange pain comes to his eyes.