Bokuhime Project

Protagonist Minato Ikusa's sister Marika has fallen into a coma following an incident at the Yuriai Private Academy for refined young ladies, so he infiltrates the school by disguising himself as a woman and enrolling under the name "Erika" to investigate. As part of this, he needs to become the most beautiful woman of the school and win a seat at the Four Princesses organization; to do this, he practices his cross-dressing skills, and partakes in a number of activities to increase his femininity, such as swimming lessons and cosplay.