Japanese schools spend a lot of time teaching the kids how to be Japanese. You’d think that would be covered by culture, by interaction with the people around them, but if there’s one thing the Japanese dislike it’s leaving things to chance. The elements of nihonjinron are deliberately inculcated in children from elementary school. The ministry in charge of education, Monbukagakusho, or MEXT in English, has national guidelines for school procedures. It’s not quite planned down to the exact date, but if kids in Kyushu are doing something on a particular day, it’s a pretty good bet that the kids in Hokkaido have it on their schedule somewhere within a few days of that. Besides pushing a home-grown romanization system — that’s useless outside Japan, confuses the hell out of kids who start learning English spelling later on, and isn’t widely used even inside Japan — and repeatedly approving revisionist history textbooks, from 2001 MEXT also started emphasizing moral education, more of a focus on the Japanese language, and fostering a sense of “Japaneseness” in children. At the same time, they paradoxically also pushed the amorphous ideal of “internationalization” in the school curriculum.
To give you an idea of how much the forms of proper behavior matter, there are mandatory moral education classes even in high school. There are also things like uniform inspections that enforce group identity. All schools that I know of in Japan, public or private, require wearing a uniform. Most schools have regular assemblies to check standards of grooming like hair length and styles (no perms, coloring, or extensions allowed), piercings (not even girls are allowed to wear earrings or other jewelry to school), and makeup. Uniform dress standards are enforced too: skirt length for girls, and sagging pants or wallet chains for boys, ties properly pulled up, shirts buttoned and tucked, etc.
These inspection assemblies usually last an entire period every month or so, teachers are expected to perform informal daily inspections, and there are occasional “uniform correctness” drives within the period between inspections, especially when non-compliance is higher than usual. Infractions are typically noted on a demerit system, and punishments like running laps before school and cleaning school areas are handed out monthly.
Almost as much time and effort is devoted to enforcing the uniform codes and formalities of politeness and “correct behavior” as to supplemental education. For example, oral communication classes for teaching English are usually only scheduled for one period a week. Inspections alone easily equal one-quarter of the class time the students might spend on practical spoken foreign language lessons. Considering that after three years of compulsory study in middle school, most students mangle simple questions into forms like, “What do you like sports?” it’s quite obvious where the priorities of Japanese schools lie.