Camper van travel

I was wondering how stuid an idea it is to hire a camer van to do some travelling round Japan for a week maybe 2?
Is it easy to hire camper vans-not bother about anything fancy?
How much would it cost for a week?
Is it a good ides for where we might go. Not sure on itinery yet but places of interest are Tokyo, Osaka, Kobe, Hiroshima. I really don't know where to go yet.
Also does anyone know about luggage storage in Tokyo. Want to take a suitcase to Tokyo(as I buy a lot there) but just want a backpack for rest of Japan. Is this possible?

Thanks in advance

A camper is not a stupid idea for rural areas like Hokkaido. But I would not recommend campers, at all, in highly urbanized regions like Tokyo-Kyoto-Hiroshima. Distances are big and streets in the cities are narrow and crowded. Finding parking for a camper in the cities must be very difficult.

I also have the same idea. But hire a campervan for long term (6 months above) may be worth to think to buy one. Anybody have any idea or website to look?