Due to her father-in-law Kazuo suffering from severe back pain, daughter-in-law Miho travels to her husband Kenichi's family home to care for him. Kazuo has always viewed his daughter-in-law as a lustful object, and finally gives in to his desires. Under the pretense of needing care, he continuously touches Miho's body, makes her wipe his penis claiming he can't bathe himself, and escalates to increasingly lewd acts. Eventually, he takes advantage of Miho while she sleeps, exhausted from nursing him. Miho is drawn into the disturbing situation, causing a dramatic shift in the relationship between her husband and father-in-law.