Otherwise, the visa may not be renewed in the future.

Whatever you do, don't let the management know about the job. If you go back to Japan, there will be a record of re-entry on your visa. When you leave and when you come back, there will be records. You can't hide. Try to find a reason to explain why you came back during your suspension.

The main question is why you dropped out of school at that time, so don't conflict between the two.