It's not for everyone. It relies heavily on trans* themes and is very slow paced. It spends the first four volumes in elementary, spends a large chunk on middle school, then high school passes in less than 40 chapters. It's a very realistic, soft paced manga. No mecha, magic, or goofy school antics here.
The protagonist of the manga is Nitori Shuichi, an elementary aged trans girl who transfers to a new school mid-semester. She has a temperamental sister one year older than her and two nice parents. On her first day of school she meets the secondary protagonist, Takatsuki Yoshino, who is a trans boy. The two quickly become friends and eventually learn their mutual interest to live as the opposite sex. Thus the story begins.
The manga conveys many emotions. It delicately discusses everything from bullying to dissolving friendships.
It's themed around puberty and those awkward teenage years. Changing bodies, friendship changes, romance, sexuality.. All while the two protagonists are transgender kids in 2000s Japan, which adds fuel to the fire.
The art style is decent at first but will eventually evolve into Shimura's signature style. I just love her art, especially when it's colored in watercolor.
The last dozen chapters are controversial and I see why. Everything goes by incredibly swift and a dozen plot points are never filled.
The manga also ends on a very ambiguous note for Takatsuki. He's a model and apparently cis identified but Shimura has said it's up for the readers to figure out the genders of the protagonists. Nitori ends with a very Shimura meta "I am a girl" making it obvious where she stands but Takasuki can go a dozen ways depending on the interpretation. Mako, another trans girl Nitori's age, has plot threads created but glossed over. Maybe Shimura didn't want to spend 6+ years on the already decade old series