Megami no Sprinter Manga

Takase is almost the opposite of his brother – weak and bad at school. He recently moved in at his brother’s house, who is a married guy. He is placed under an exceptional coach to improve his physical health, and the coach – also known as ‘Venus of Track’, is none other than his sister-in-law. She is developing a new technique to improve at a faster rate by managing testosterone levels in the body; in other words sexual desire management. She calls it absolute obedience. And Takase has to go under it to improve himself.