Only ever got stopped once in 10+ years, and that was for the crime of riding my bicycle without working lights the short distance to the local konbini, tragically for them they made the mistake of stopping me in the konbini parking lot, not on the public road, so they had to resort to radioing in to the 24/7 Bicycle Registration Control Center, which I imagine is a cavernous bunker beneath the Keishicho full of people hunched over workstations plotting the course of stolen mamacharis while a bank of wall-mounted screens shows scenes of bicycle-related hotspot activity across the Kanto area, and they got excited for a brief moment as they couldn't find the registration sticker, which the guy in the shop had stuck somewhere inconspicuous, but ultimately they were satisfied that the registration matched the name I gave them ("Colonel Sanders") and sent on my way with nary a check of any ID, presumably hoping I would be dumb enough to cycle off down the public road.
You must look like the Colonel. No ID check required.
I wonder how many times in the history of the Japanese police force a meeting has been convened to discuss upgrading their bicycles? 0?