Minato learns from Chinu Kawakubo about a promise they made in the past. To fulfill their promise, he decides to join the water polo club, much to the delight of Eitaro Oka and the team captain, Jo Jojima. They utilize his fame to recruit members, but...

Amihama stubbornly refuses to join, but a certain something changes his mind and Yamanami's Water Polo Club is officially underway. Despite the team struggling with the basics, they find themselves playing their first practice match.

It's finally time for their second match of prefecturals--the long-awaited showdown with Shogakukan. Minato, Eitaro, Jo, Amihama, Ejiri, Babayaro, and Ushimado join their seven hearts as one and challenge the best team in Japan.