Saikyou no Furyou ga Nyotaika! Tsundere Ore Kuchou no Bishoujo ni!? ~Baka! Naka ni Dasu Yatsu ga Aru ka, Ore ga Ninshin Nante Arienee!~

Subaru was the hardest of a gang of thugs, directly descended from martial artists.
How does a guy this tough end up cursed as a big-breasted woman!
Feminized Subaru has to fend off perverts and find a way to return to normal.
Meanwhile "her" body is subjected to nonstop erotic happenings.

[from DLsite English]