Traffic Control and Traffic Violation

Q4 Is it illegal to put a vehicle's license plate in the position that it cannot be seen clearly?

A4
It is against the Road Trucking Vehicle Law if you remove, fold or cover a part of a license plate with a tape or other material to make the plate not seen clearly.
As for a motorized bicycle, it is also a violation of the Osaka Prefectural Road Traffic Regulations to do so.