Naoya Inaba, who spends the majority of his adolescence abroad, returns to his hometown for his third year of high school. He enrolls in Saku High, which he admires thanks to one of its graduates, Yoshio Kurosawa, a yankee who saved him from bullies and who encouraged him to never give up in pursuit of his dreams. However, to his dismay, he finds out that Saku High is inhabited by low-lives who resign to being underdogs in the town, and the school itself is about to be closed due to a lack of popularity. Naoya determines to resurrect the spirit of old Saku High by creating a water polo club to compete with Suiran High, a private rival high school whose successful water polo team brings the town out of obscurity. Needing seven members to start the club, Naoya builds friendship with the playful trio Tomoki Kimura, Kohei Shimura, and Shinsuke Kato, the pessimistic but good water polo player Ryuji Mifune, as well as the wild Ryo Chiaki and his friend Koki Miyaguchi. He is assisted by the school math teacher Chiharu Aoyama for advisory purposes. Naoya also gets emotional support from his childhood friend, Nagisa Iwasaki despite her being associated with Suiran High's water polo team, who grows to accept the current Naoya after her initial disappointment of seeing him changing into a yankee. Slowly, Naoya learns about the team's problems and bring them from their sulking with a determination to beat Suiran High, whose water polo team is aced by Torao Kitajima, a frenemy of Ryuji who strives to beat the latter to win the heart of Rei Fujisaki, despite the fact that Rei is unconditionally in love with him. Later, Naoya also reunites with Kurosawa, but his expectation is temporarily stripped when he learns that Kurosawa has given up his pride on Saku High. During the Inter-High tournament against Suiran High, Naoya overcomes an injury brought upon by a member of Suiran High and manages to score his team's victory. After the match, Naoya confesses his feelings to Nagisa, who accepts. The epilogue, narrated in a letter from Nagisa to Suiran High's water polo teams' adviser, Mayu Shoji, tells of the events happening after the Inter-High tournament: Saku High is successfully prevented from being closed and its water polo team continues to thrive; Ryuji competes for the national championship team thanks to his performance in the Inter-High tournament; while Kurosawa has regained his faith in Saku High and is training to be its teacher. The series ends with Naoya saving a boy from bullies and advising him never to give up, just as Kurosawa has done to him years before.
