Clever water saving idea!

These fixtures were standard items everywhere in Japan until a few years ago. They are gems of green sanity, cleverly designed, easily retrofitable, and impossible to find in the US. It's a sink for the top of the toilet tank, so that before the water enters the bowl during a flush, you get to wash your hands with it.

Makes perfect sense! Why waste the water you used when washing your hands? Let it do double duty as water to flush the toilet too.