Hourou Musuko Complete Series

 AKA - Wandering Son

 Shuicihi Nitori appears to be a shy and quiet preteen boy, when he transfers to a new school he quickly makes friends with the tomboyish Yoshino Takatsuki who sits next to him. It soon becomes apparent that both Shucihi and Yoshino are more than simply a sensitive boy and masculine girl, they both are transgendered. Together they decide to take the first steps toward becoming the people they want to be.