Wataru, who has failed the university entrance exam twice, is what people call a hikikomori. Unable to bear seeing this, his father asks his friend's wife, Yuu, who used to be a private tutor, to be his private tutor. Yuu readily agrees and teaches Wataru, but is troubled by his complete lack of motivation. Thinking about how to get him to concentrate on his studies, Yuu uses her beautiful body to come up with all sorts of naughty schemes for Wataru...