Ryoji has always been like a brother to his cousin, but all that changes when Ryoji witnesses his cousin's wife pleasuring herself one night. Then the next day, Ryoji walks in on Kasumi in the shower. Unable to get the image of Kasumi's massive breasts & her masturbation out of his mind, Ryoji makes it his mission to satisfy the unfulfilled woman. However, Kasumi's sister, Harumi, and Kasumiís own daughter, Mio, have their own plans for Ryoji . . . .