Mother Reiko and her son Kenta end up living in a defective house. They are troubled by a broken water supply and have to call a plumber to fix it, but mother and son decide to conserve water until the day of the repair. However, when Reiko starts saving water by taking a bath with Kenta, Kenta gets an erection when he sees her naked body. Reiko notices the change in Kenta and realizes that her son is now a man...