I have a few ideas. First of all, Junior High School in Japan is intense. Take all of your preconceptions of American JHS and stuff them. They have been preparing their whole lives to perform for these 3 years. This is it. They have sports or band practice before and after school. They practice during school breaks. Many attend juku (cram school) for English. We had the annual school festival last week and sports superstars were playing koto. Band members were doing English speeches. Dancers were doing Taiko drumming. If a student says they practice shodo (Japanese calligraphy) they will always say they've been doing it since they were 4 years old. Their lives are incredibly scripted, the education based on rote memorization and regurgitation and there is little to no free time. When asked what they did over summer vacation, most of my students went with their families to the sea - for 1 or 2 days of a 4 week break. All said they studied. When pressed, some played video games or watched tv.
Here's the thing, most students are happy as clams. They are doing what they're supposed to be doing. They are excelling at it. They are part of the group (the most important thing in Japan). They are standing out only for winning competitions. Otherwise, they are blissfully blending.