Mary has lost her husband and lives with her ex-wife's son. She had a faint romantic feeling for her son, who somehow resembled her late husband. We went on a hot spring trip just the two of us... even though we are parents and children according to the family register, we are strangers. Even though they know this is not true... there is a forbidden bond that connects the two of them. Unable to resist the pleasure of immorality, the two make love to each other on a night in Joshu... They can't hold back any longer. The sounds of panting from parents and children are endless.