Hiroshi, whose girlfriend is pregnant and decided to get married, is currently in the process of registering their marriage. His girlfriend's mother lives alone in the same city. Due to his girlfriend's pregnancy, Hiroshi has been relying on her mother for various things, and with frequent visits home from the hospital, he's been finding himself increasingly drawn to his mother-in-law's voluptuous figure swaying under the same roof. Unable to resist the temptation, he succumbs to his unchaste impulses...