Because her weight increased rapidly, Kokoro decided to hire a Yoga instructor to practice with the hope of losing weight and having a slimmer waist. However, if she gets this, she loses the other. In exchange for getting rid of excess fat, she has to use her virgin body in exchange. The reason is also because that Yoga instructor is too handsome and lustful. He always knows how to please women, perform provocative movements, stimulate young girls' arousal, then freely touch or even have sex extremely easily.