S1, E5: Sannan has been using materials left behind by Kodo to continue to try to improve the medicine in secret. He drinks the medicine and transforms into something which is no longer human. After seeing the wound Sannan infected on Chizuru heal in an instant, Hijikata asks her if she's a rasetsu, but... Later, the commotion over Sannan adds to the decision to move the Shinsengumi headquarters to Nishi Hongwanji. Chizuru continues to search for her father, but she is unable to find any clues to his whereabouts. Then one day, Chizuru happens to overhear Okita's secret.