Clean the washbasin cup. I found a product called "Tumbler & Stand that runs out of water and flows" and bought it.
A product that includes a tumbler (cup) and a special stand. If you turn the tumbler used for brushing your teeth upside down and hang it on the stand, water droplets inside the tumbler will fall. The tray at the bottom of the stand naturally flows down to the washbasin. It is clean and easy to use and easy to maintain because it is antibacterial and antifouling. There is also a non-slip on the bottom of the stand.
Simple and stylish, looks like a mushroom somewhere?
Mechanism of dripping water flowing to the washbasin
There is a non-slip on the bottom of the stand
A washbasin cup that may grow mold and germs if water is left on the bottom. If you haven't taken any measures, why not rely on such an item that can be drained and dried naturally? "Tumbler & Stand that runs out of water" is sold at various mail-order sites. I bought it from Amazon.co.jp and the price was 498 yen.