Yukito, being the ambitious fucker he is, applies to be a domestic servant at a mansion. The landlady tells him he can only get the job if he masturbates in front of her. He gets the job.
Soccer player Hayasaki Ryoushirou returns home with a sports injury. When his four older sisters find little sister fetish material in his luggage, the only possibly therapy for his unacceptable (and non-existent) lolicon fetish is sex with his busty older sisters Yuri and Mio.