Each year the youth of Japan sit down for an exam that will decide their lives. The entire year will sit down together and they all complete the same test on the same day. Make it and you're into university, fail and it's the end as far as many will feel. The pressure is immense and parents have been building their children to this day for years sending them to cram school after regular school every night for three extra hours of tuition until the kids are physically and emotionally exhausted before returning home to complete their homework.
The system hasn't changed for years but once in to university it's almost impossible to flunk out. Several years of partying ensue occasionally interrupted by lectures. The system is pretty much universally loathed but as it's the only system, it's that or nothing. As a result the juku (cram) schools are, well, crammed with kids whose parents are competing with other parents as much as their children are competing with each other.
Juku extends from not just the children aiming for university but often as far down the age ladder as getting a child into the right kindergarten. The limitation on places means once one parent forces their child into the process the remainder feel obligated to provide their child an equal "opportunity". And the children stress out. The system should be modernised in reality. No one should be obligated to force their children to rote learn simply to beat another child to a place. A career should depend on skill and ability not the name of your school. But in the mean time, good luck to you all this weekend. Relax, life is more than a single exam.