Yoshino's son, Masayuki, discovers his mother having sex with another man. Shocked by the encounter, Yoshino finds herself unable to satisfy her awakened desires through mere perfunctory sex. She begins masturbating in Masayuki's futon, but is soon caught by him. Unable to resist their mutual lust, mother and son are pulled into an uncontrollable whirlpool of passion. The forbidden relationship between them grows ever deeper.