In Japanese middle schools and high schools, students are indeed divided

into different classes, and each class follows the same set schedule

throughout the day. It means that students will have the same classmates for

all their classes, unlike in the U.S where students may have different

classmates for different subjects.

The class as a whole moves from one subject to the next together. This kind

of system promotes a strong sense of unity among the students and

strengthens the class identity. They also eat lunch together in their

classrooms, and are in charge of cleaning their own classrooms and other

areas of the school.

However, when they reach high school, some schools may begin to offer

elective classes where students from different classes can mix, especially

in the third year (senior year) where more specialized education according

to the course (like science & math course, humanities course, etc.) may be

introduced. But the core idea remains the same, where a student spends most

of their school days with the same group of students.