Originally Posted by
JL41
It's not about bending the rules. In many countries, the law gives immigration officers (the ones at supervisor level, anyway) a level of discretion. It can often be possible to grant probationary entry permission for a limited time. It certainly happens here in the UK. That said, I'm not familiar with the level of discretion Japanese officers are given.
This is Japan though. I doubt there was much if any discretion available on the part of the immigration officer and OP was 30 hours early (over a full day), not 3-4 hours.