Due to a certain incident, a high school girl named Saya lost her memory. She doesn't know where she is. She doesn't know what to do next. She barely remembers her first name—Saya. Everything else is lost in a fog. She doesn't remember her family's faces, her friends' names, or even the school she is supposed to attend. She doesn't even know where her home is.

Although Saya doesn't remember, she had come to visit from Zeta City in the neighboring Zeta Prefecture. There, she happened to intervene in a dispute between a man and a woman. In the process, she hit her head hard against a wall and lost consciousness. When she woke up, her memory was gone. There was no one around. The man and woman involved in the dispute had already fled. Left all alone, Saya wandered the streets, nearly crushed by anxiety. Eventually, she reached a small park. The cold evening wind brushed against her cheeks. As she sat on a bench, at a total loss for what to do— Guest appeared.

No.03