Related to this, a good idea when traveling internationally is to carry contact information for a local embassy or diplomatic branch of your home country.
One thing a traveler could do for some peace of mind is notify an embassy of the trip ahead of time, such that in a police hassling scenario someone on scene can call and get official confirmation in Japanese of who you are and what you're doing, act as an interpreter, etc.
One thing a traveler could do for some peace of mind is notify an embassy of the trip ahead of time, such that in a police hassling scenario someone on scene can call and get official confirmation in Japanese of who you are and what you're doing, act as an interpreter, etc.