That would probably just result in a ticket, which must be paid immediately at the police station. But if you'd had one drop of alcohol in your system, it would

That would probably just result in a ticket, which must be paid immediately at the police station. But if you'd had one drop of alcohol in your system, it would have meant jail time. The DUI limit in Japan is much lower than in the US and even if you haven't been drinking the limit doesn't matter if the cop judges you to be impaired.