The events of Onidamashi-hen are shown from the perspectives of Rena and Satoko. Rena becomes increasingly upset with her father's affections for Rina Mamiya, a showgirl at a gentleman's club frequented by her father. Satoko injects Rena with H-173 while she sleeps at the nurse's office. Rena learns her father has been overspending money on Rina taken from the settlement from his divorce from Rena's mother. Rena reflects on her parents' divorce and concludes she did not try hard enough to stop the divorce and that some people do not deserve kindness...