Toilet low tank with washbasin

In Japan, the toilet, the washroom, and the bathroom are a separate room in many cases.The small washbasin for washing hand was attached to the toilet room.
This itoilet low tank is what attached to the low tank the function to wash a hand, and since it washes a hand with the water for suppling to a tank, it contributes also to water saving.
And since the space which installs a washbasin is unnecessary, it also becomes saving of space.
Although not all person forget to pour water after using a toilet, washing a hand tends to forget.
If a lever is turned and water is poured, since water will come out from the water tap which is at hand, those who have forgotten to wash a hand will also wash this toilet.
All the water collected on a tank is not used for washing of hand, and a part of water flows into a tank directly.