Tokyo rent is too high to live alone, so a man moves into a shared apartment and discovers that his roommate is a woman. Having never had a girlfriend, he gets hard from her scent alone, then struggles even more when her underwear hangs in plain sight. Once she grows comfortable around him, she wanders through the apartment in lingerie, leaving him painfully aroused every night. One day he catches her masturbating. She is clearly horny too, and when she sees his erection, the atmosphere suddenly turns sexual. Shared living may be better than he ever imagined.