Despite the country's falling birth rate, Japan has seen a huge increase in enrolments at cram schools because parents believe that standards at state schools are falling.
Nichinoken, the nation's biggest chain of cram schools, or jukus, has announced a 6 per cent increase in enrolments for this school year, which began in April - approximately double its average annual growth.
The rival Waseda academy has predicted its profits will rise by 49 per cent to a record 810 million yen (pound;4m) for the year ending March 2006.
The renewed interest in jukus is said to be caused by the government's launch of a "relaxed education" policy in which the workload of a typical middle-school student has been cut by up to 30 per cent.
Many parents say the reduction has eroded state-school standards, with jukus now filling the gap and benefiting from parents' fears that children without extra lessons will fall behind.
Typically, a Japanese 13-year-old will attend juku classes four times a week (5-8.30pm) and take tests on Sundays. Government statistics show that more than 70 per cent of the country's 15 million schoolchildren will seek some sort of private tuition by the time they enter high school. Parents spend an average of pound;250 per child per month on juku classes.
"For children, this has meant they are increasingly seeing juku as a place to learn and regular school as a place to have fun and meet their friends," said Ushio Hirasawa, of the Hakuhodo Institute of Life and Living, a think-tank set up to research everyday life in Japan.
Its report - What's going on in today's kids' heads? - found that school is "a place to make friends and have fun, but in terms of where they learn their three Rs, it is cram school, not regular school".