Trans'2 ~Boku to Atashi to Koibito to~

The main character moves into an apartment with his childhood friend Mizuki to attend university.
Soon after moving in together, he accidentally discovers that Mizuki is a closet crossdresser.
Assuring him that he'll look really good in it, Mizuki persuades the protagonist to dress in drag, too.

Even though at first he was a bit hesitant to the idea of crossdressing, he quickly gets hooked and begins to live a double life.