"I also hear that the japanese pilots fly their schedule, then are basically always on-call for the other days."
On a normal monthly schedule, there are 2 kinds of days off. "H" days off (10 days per month) which are guaranteed days off, and blank days off which means that the company can call you for flight duty. If you do not answer the call, you are obligated to call them back within 24 hours, which by then they would have already found someone else to fly.
I hope this answer your questions.