Calling the police is necessary even in a small traffic accident. It is a legal duty for everyone to call the police, and it's an important chance to prove the accident officially. Without the step, you cannot prove it to an insurance company when applying for its payout.
Under Japanese law, a negligent driver in a traffic accident has three liabilities: civil, criminal, and administrative liabilities. Paying compensation is under civil liability. Fine or imprisonment will be imposed under criminal liability. Suspending or cancelation of the driver's license is under administrative liability.
As of Dec. 1, Japan toughened penalties for driver's smartphone use. Any drivers should not watch smartphones for more than two seconds while driving vehicles.
