Naoto, having been dumped by his girlfriend, dejectedly steps outside and catches his mother Yuriko urinating in the garden. Unable to hold it in, she relieves herself, and witnessing this scene unexpectedly arouses Naoto. He gives Yuriko a strong diuretic tea, causing her to urinate again, then boldly assaults her the moment she finishes. Though Yuriko tries to resist, her body betrays her words, growing hot with desire as long-forgotten pleasure surges through her entire being. Eventually, Yuriko begins craving Naoto as well, and their relationship takes a new, forbidden turn.