Check this out: Now available at Narita International Airport is a company called DreamDrive which leases van + RVs to renters to drive around Japan. The vehicles are upgraded with nice interiors + a bed for sleeping. They also have power, lighting, storage, a sink, and some have a large roof rack. It’s a cheap way to see Japan + rent a vehicle at the same time.
If you’re planning on seeing some of the Japanese countryside while in Japan, and want to save money, DreamDrive might work. They also sell their vans.
Check them out: