A first-year college girl named Yuka was recruited! She studies medicine and has a cute, infectious smile. When asked if she would help develop a cleaning seat device by simply doing some part-time work, she cheerfully agreed. They started off by measuring her anal opening, size, progress rate, position, etc., all while enjoying her beautiful rear end. Next, they used their tongue to stimulate her anus in order to replicate the gentle water flow of a cleaning seat machine during research. After finishing up with the anus, they moved onto vaginal (pussy) research. As thanks for her participation, he gave her a blowjob before finally fucking her tight hole raw.