Replying...
Intro. Haruka, a weak and often bullied 10 year old boy, gets caught up in the mysterious experiments of a burly man. Instead of being a strong adult man, Haruka awakens in the body of an adult female bodybuilder with extreme hyper-muscular proportions, Z-cup breasts, and an incredibly massive and curvaceous physique. Even though he now has the body of a tough, dominant athlete, Haruka's soul is still that of an innocent and confused 10 year old boy. Trapped in a giant body he doesn't want, Haruka must adapt to his new life while finding a way to return to his old self.

"Dream of Becoming a Muscular Man Ends Up Being a Mature Bodybuilder's Wife!"

@Akira