One day, Sui tells Biki that she already knows the cause of her disease, there are Mushi, mysterious beings and the focus of the series, living in her eyes. She also tells him that when she closes her "second eyelids", she can see a river of light in the otherwise pitch-darkness. When she tries to get closer to the river, a mysterious man warns her not to, that the river isn't safe to look at for long. Meanwhile, Biki's mother's worst fear is realized, as her son catches Sui's illness. The next day, when someone comes to bring Sui her food:
Sui: Biki? Biki? What's wrong?
Biki's mother: Biki...won't be coming back. He's caught your illness. I know you didn't mean it...It's not your fault. It's my fault for feeling sorry for you.