OVA: Forbidden All Hard! Free! : Season 2 Episode 14

Haruka and the others go to Samezuka Academy's Culture Festival, where Rin and the rest of the swimming club are hosting a maid café. Both the Iwatobi and Samezuka teams decide to participate in a watergun survival game across the campus, with Haruka, Sousuke, Nagisa, and Momotarou on one team and Rin, Makoto, Rei, and Aiichirou on the other. After several mishaps and plans gone astray, the match boils down to a standoff between Haruka and Rin, which Rin wins due to Haruka's affinity for water. At the end of the day, the eight of them take the time to get to know each other better.