18+ Megami no Sprinter

A brief description of the Megami no Sprinter manga:
Takase is almost opposite of his brother weak and not good 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 know as ‘Venus of track’ is none other than his sister in law. She is developing a new technique to improve body at a faster rate by management of testosterone levels in the body, in other words sexual desire management. She calls it ‘absolutel obedience.’ And Takase have to go under it to improve himself. This changes his life drastically, read and find out more.