Thirty-Nine
Explorer

Kei car + camper van = kei campervan!
Admittedly, this wouldn't be something you'd want to travel the Interstate with, but it'd probably be great in Japan, and you could probably get around OK on highways in the U.S. I kind of love it.
Here's the article I wrote about them.
http://crankshaftculture.com/2017/01/18/behold-the-kei-mini-campervan/