Naoya Inaba (Nakajima Yuto) grew up abroad and from his childhood experience, he thought “yankees” were the strongest heroes (in Japan "yankee" refers to delinquent youths). He was influenced by Japanese yankee manga while abroad and because of his own experiences and mangas, he is always full of chivalrous spirit. Naoya arrives to spend a year in a high school in Japan. He attends a technical high school which emphasis on the location being center of "water polo supremacy" but is on the verge of closing down. Naoya admires the school because a yankee, whom he admired as a child was once a student there. However, he soon realizes that there are no real yankees like hero figures, only students who spends their days meaninglessly. Naoya is disappointed and decides to do something about it.
Sawatari Goro now works at Akado High School as a vice principal. Although the head director of the school board speficically orders him to handle the problematic class 3-D, the students are just too much for him. So Sawatari goes far away to a southern island to search for Yankumi, and convince her to work for Akado. Yankumi accepts the offer, only to find that her class (again) is full of punks, where two rival groups of students are always at each other's throats. Will Yankumi's strong belief in students and teaching work this time?