 Separate rooms for the Japanese toilet, sink, and "ofuro" (bathing room) are common.Small apartments, however, frequently contain a tiny single bathroom called a unit bath that contains all three fixtures.A small sink may also be built into the top of the toilet tank – there is a tap, with the top of the tank forming the sink, and the water draining into the tank – which runs during the flush cycle; this is particularly common in mid-20th century buildings.