Let this be clear: Wandering Son is possibly the best story about transgender characters I've experienced in any medium, period. (Granted, I haven't seen/read that many.) It's about two fifth-graders, Shuichi and Yohsino as they begin to come to terms with, and practice, their preferred identities. Shuichi delights in performing a female role in the class play, Yoshino revels in uniform-clad anonymity on the opposite side of town, etc.
Creator Shimura Takako really puts the "slice" in "slice of life," delivering the story one little vignette at a time. It makes the transitions feel a bit jumpy at times - it can be hard to tell if two scenes are supposed to be one class period or a whole day apart, for example - but ultimately benefits the pacing. Takako delivers layer after layer of emotional punches, builds up to a major heartbreaking (or heartwarming) blow, and begins the process all over again. Her artwork fits perfectly as well, with characters drawn sweetly enough to show off their innocence without getting overly "cute."
As a special feature, the English version by Fantagraphics includes a short essay on the use of honorifics in the Japanese language. While honorifics are largely incidental in most manga, their relationship with status and gender give Wandering Son yet another sheet of emotional substance.