Takes place over one day, around 9:00 - 18:00
You'll meet up with the rest of the interviewees and get told a bit about the company and Japan. It's good to be keen and ask a lot of questions, it'll stroke the manager's already inflated ego.
The manager will treat it as quite informal. You'll do a couple of group or pair tasks, but nothing too taxing. This is just a time for the manager to decide who he thinks the children will like, who he likes and who he thinks he can control.
At the end, he will invite you down for drinks. If you don't go along then don't expect an offer. He wants to see what you're like in a social environment. He'll regale you with stories of past employees, and the more you laugh and ask questions, the happier he'll be with you.
Best advice is start to leave when the others start leaving. Being the first one isn't the best, but being the last also isn't the best.