Princess 69: Midnight Gymnastics

When his sister Miku goes missing, Fubuki's search leads somewhere stranger than he expected — an underground world called 'dark rhythmic gymnastics,' where competitors blend athletic technique with something far more provocative than anything you'd see at a legitimate meet. Miku's classmate Tomomi fills him in on the situation: Miku has gotten pulled into this secretive competition, and getting her out isn't going to be simple. Fubuki's solution is to step in as a coach and navigate this shadowy circuit from the inside. That's the setup across these two OVA episodes — a rescue mission wrapped inside an adults-only underground sports drama with a school backdrop. The rhythmic gymnastics angle is genuinely specific and niche, which gives it a different texture compared to more generic entries in the genre. If you've watched Shintaisou: Kari and wanted to see a story branch that leans harder into the competitive underground angle, this is essentially that. The character designs are detailed and the animation holds up for what it is. It's a short watch at two episodes, adapted from a visual novel, so the pacing moves quickly without a lot of setup padding. Fans of mature school-themed OVAs from the mid-2000s will find this familiar territory.