I'm a High-schooler Boy but got Gender-Bent into a Gal

Danshi Kokosei Dakedo Gal ni TS Shimashita

A Cutie Gyaru Goddess turns high school loner Junpei into a busty gyaru! Now he has to survive an all-girls' school full of gyarus and collect their "gyaru power" to turn back into a boy! (Source: Kadokawa)