School of Rock a la Japan - can you guess the ending?

The Japanese version of School of Rock is a 2005 picture, "Linda Linda Linda" (lyrics from pop song, probably composed for this movie by a former Smashing Pumpkin member) - about a trio of high-school girls who need to perform for a school fair and lose their lead singer - sounds like a million others, and it is like a million others, except for the setting, which gives U.S. viewers a window on what high-school life is like in what seems to be an industrial small city in Japan - it's very different from here, if the film is accurate, students far more deferential and shy and conventional that in any typical U.S. high school. I wanted to like the film but just never warmed up to it, and oddly the films seemed to melt away in our Blu-Ray and died about 65 minutes in, so I don't know the conclusion, though any idiot can make a solid guess. Part of the charm of the film I suppose is that much is left unsaid and unexplained: there's some kind of falling out among the band members before the start of the film, causing one to walk and somehow inexplicably causing another to injure her hand - we don't know how or why. The girls recruit the Korean exchange student to join the group - again, totally inexplicably. She doesn't know the music, she's not popular or glamourous. In another picture, this would be a huge plot element: why did they have to work with an unpopular girl? how do they get along? does she change? does she win them over? and so forth. Here, it's just a given. The main problem with the film is that there are no obstacles and no antagonists - no angry parents, jealous boyfriends, rival band, internal rivalries in the band: the girls just move forward with their project, getting gradually more competent, toward the obvious conclusion that I never reached.