It seems to be easy to use even in a narrow washbasin. I tried a product called "Petitcle Zeal Toothpaste Cup", which is a washbasin cup sold by Mana.
It seems that it is a long-selling product with a cumulative total of over 800,000.
A product that includes a toothpaste cup and a stand (sucker and stick). The suction cup has a vertical hole and a horizontal hole, and you can choose either "flat storage" or "wall storage" depending on which way you insert the stick.
A set of a cup and a stand (sucker and stick)
Insert the stick vertically and
If you attach it to the base of the washbasin,
Insert the stick sideways and
If you attach it to the wall of the washbasin,
By storing it upside down, it dries faster and can be used hygienically. If you are worried about the water stains that collect in the washbasin, why not use it? I bought it from Amazon.co.jp and the price was 414 yen. It is also available on other online shopping sites.