Gender bending in movies is usually a cue for comedy, especially when taken to more fantastic extremes, as when Debbie Reynolds plays a womanizer reincarnated as a woman in Vincente Minnelli's "Goodbye Charlie" (1964) or Satomi Kobayashi and Toshinori Omi play teens who switch bodies and minds in Nobuhiko Obayashi's 1982 film "Tenkosei (Exchange Students)."

Shoko Kimura's "Koi ni Itaru Yamai (The End of Puberty)," which screened in the Forum section of the Berlin Film Festival this year, does work strenuously for laughs, but for all the manga-esque screeching and mugging and jumping in and out of closets, it also wants to say something serious about sexual identity and gender roles. Are we ultimately defined by what's between our legs, or can we transcend that in our search for love? Can opposite-sex couples really meld into a unisexual one, as Plato once philosophized?

This is a heavy assignment for a first feature about a bubbly teenager with a crush on her nerdy high school biology teacher, but Kimura, who both scripted and directed "The End of Puberty," avoids up-front morals and messages, preferring to make her points more dramatically, imaginatively and strangely.