Free! Eternal Summer: Kindan no All Hard!

With the pressure of competitive swimming briefly behind them, the Iwatobi and Samezuka swimmers gather for a very different contest: a campus-wide water-gun survival game. Teams are mixed across the two schools, putting Haruka, Sousuke, Nagisa, Momotarou, and their friends in combinations that turn familiar rivalries into tactical chaos.

Hallways and classrooms become a battlefield where speed, teamwork, deception, and ridiculous determination matter as much as athletic ability. What begins as harmless fun quickly becomes fiercely competitive, revealing just how seriously these swimmers can take a game that has nothing to do with a pool.