Japanese films with transgender themes, both fiction and nonfiction, are no longer a rarity. Among the former are Naoko Ogigami’s 2017 “Close-Knit” and Eiji Uchida’s upcoming “Midnight Swan.” But no one, I imagine, has done a deeper dive into one Japanese transgender life than Miyuki Tokoi.

She filmed her documentary “Zero as You Are” over a period of nine years, following Takamasa “Sky” Kobayashi from adolescence to adulthood and through transitioning from female to male. She then edited nearly a decade’s worth of footage down to a compact and impactful 84 minutes.

Sky (a self-selected English name) was diagnosed with gender identity disorder (GID) at 13. (The American Psychiatric Association reclassified GID as “gender dysphoria” in 2013 and the latter term has since come into standard use.) When we first meet Sky at age 17, he is outspoken from the get-go, telling a rapt audience at a speech contest that he has two goals: First, to become officially registered as male and live as a man and, second, to train as a voice actor.