My children are back in school after two weeks of winter vacation. We went skiing and took a few day trips around Tokyo, but the boys spent most of their vacation playing, reading and relaxing. Some of their school chums, however, had no break at all. They spent the entire "holiday" studying for middle-school entrance exams.

Take their friend Hiro, a sixth-grader who will take the entrance exams for five middle schools. Hiro is not one to wait until the last minute to study. For several years now, he has attended a juku (private "cram" school) after school and on weekends to prepare for the exams.

But since middle-school exams are held in January and February, winter vacation is the last chance for a big push. Hiro's parents paid 55,000 yen for a toki koshu (special winter-vacation course), which consisted of eight days of intensive classes. Hiro put in eight-hour days at juku, then went home for dinner -- and three or four hours of homework.