Car Rental at Kumamoto Airport (KMJ)

You need an International Driving Permit (IDP) — your US license alone is not valid. Get one from AAA before departure (about $20). IDP must be issued under the 1949 Geneva Convention. Carry both your US license and IDP at all times. Police checkpoints are common, and driving without proper documentation results in fines up to ¥100,000 ($700) and vehicle impoundment.

Yes, expect a learning curve. Japan uses LEFT-hand traffic with RIGHT-hand drive vehicles — the opposite of the US. Key adjustments: (1) Roundabouts — traffic already inside has priority; (2) Stop lights are vertical, not horizontal; (3) Right turns on red are illegal; (4) Some narrow rural roads have no center line. Practice in a quiet area for 30 minutes before hitting highways. Fatal accidents per kilometer are 3x higher for foreign drivers in Japan.

Tolls are PRICY — a 2-hour drive from Kumamoto to Mt. Aso costs roughly ¥2,500-3,000 ($17-21) one-way. The Kumamoto-Miyazaki expressway alone runs ¥3,240 ($22). Rent the ETC card at the rental counter (¥330/day, ~$2.30) — this saves cash lanes and lets you use expressway discounts. Without ETC, you pay full cash price at toll booths. Budget ¥8,000-15,000 ($55-105) daily for tolls on a full day of sightseeing.

REQUIRED for Mt. Aso routes from November-March. Even though Kumamoto city stays mild (5-12°C), mountain roads leading to the caldera (Route 442, 325, 57) accumulate ice and snow. Rental companies offer winter tires for ¥2,000-3,500/day ($14-24). Snow chains cost extra. Chains must be installed on-site when road signs display 'chain requirement.' Aso Volcano Museum checkpoint may turn you back without proper equipment. Book winter tires at reservation — availability is limited December-February.

YES, almost certainly. Most Japanese rental companies charge 'young driver fees' for drivers under 25 years old — typically ¥1,100-3,300/day ($8-23). At 22, expect to pay on the higher end. Some agencies (Times, Nissan) charge flat ¥2,000/day regardless of age below 25. Budget an extra ¥15,000-30,000 ($105-210) for a 10-day trip. Consider booking with companies that waive fees at 21+ (Nippon Rent-A-Car sometimes does).

Yes for regular gasoline; NO for late-night stops. Most cars in Japan run on 'regular gasoline' (not premium). Gas stations are abundant in cities but become sparse in the Aso region after 7-8 PM. Many rural stations are unattended and cash-only. Download the 'Goo' or 'Navitime' app to locate the nearest station. Fill up before heading to Mt. Aso or rural temples. Full-tank policy applies — return the car with the same fuel level to avoid ¥300-500 ($2-3.50) service charges for refueling.