Some contract companies going fishing to increase their data base, some will try and make you sign exclusive contracts to act as sole agent - for positions that may not really exist or may exist...one day.
Japanese contracts have never been at the top end dollar wise and subject to win/lose on exchange rates but seen as reasonably good conditions, fairly honest dealings regards payments etc and if you can play the game their way ops wise then fairly stable.
All just IMHO of course.
Cheers