http://www.easystill.com/
This company makes a counter top distiller for less than $200 that makes 4 gallons per day. They make them with different voltages for Europe and South America, so they probably make a unit that will work in Japan. They ship worldwide.
Probably easier than trying to build one yourself.
Here's a video by a guy who built his own for less than $100 with a pressure cooker, small radiator and a fan.
Homemade Water Distiller Makes Purified Water - Associated Content
Wicked clever!