Nao, a 23-year-old office worker, grew up as the one girl in a household where her three brothers and parents were all obsessed with muscles. Nao managed to find a job and leave her house of meatheads, but is forced to return home when her office is struck by layoffs. However, she gets pissed off and runs out when she discovers that her room has been invaded by her brothers. Her big brother, Subaru, runs into the park to get her, but their argument is broken up by 35-year-old associate university professor Asuka Himori. The two of them end up meeting again at a marriage mixer and they end up hitting it off. Tonight's their first night together... but when Nao sees Asuka's naked chest, she can't help but run away at the sight of his muscles...!! No one said that a serious professor would be that muscular!! And it's not just his body, but his personality, too!?