It's a hassle, but the check is over in 5 minutes. Show your photo id (which Japanese usually carry, and foreigners are required to) and if the names match you'

It's a hassle, but the check is over in 5 minutes. Show your photo id (which Japanese usually carry, and foreigners are required to) and if the names match you're good to go. If the bike isn't reported stolen and your ID is good they'll send you on your way. If it's reported stolen you'll have to go to the police station to do some paperwork even if it is your bike.