Kouitten -Dansou Bakunyuu Joshi no 3-nenkan ni Wataru Zecchou Choukyou-

Aoi is a pretty girl attending a girls-only private school.
As intelligent as she is beautiful, she still ranks second to her idiot brother who is sure to doom the family if he inherits everything.
What's a daughter to do? Aoi decides to crossdress, attend her brother's school, and graduate pretending to be a boy.
It will be a grueling three years of secrecy...

[From DLsite English]