Ep. 12: Kagari regains memories of being Mayuri's mother after hearing a recursively passed-down song.

Kagari collapses after hearing Mayuri sing, prompting Rintaro to suspect it aids her memory recovery. Tracing the song’s origin reveals a chain: Suzuha learned it from Yuki in the future, who learned it from Rintaro’s mother, who claims Rintaro sang it to her during his early mad scientist phase. Later, while visiting Mayuri’s grandmother’s grave, Kagari hears the song on the radio, enters a daze, and narrowly avoids a truck. This incident triggers the return of her memories, revealing that Mayuri is her mother. The narrative concludes with the revelation that Rintaro originally learned the song from Kagari years ago, just as a mysterious organization spotted her.

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