Will this make your smartphone life much more comfortable? I found a product called "Card Stand Case" at the 100-yen shop CAN DO and bought it.
A type of card case that can be attached to the back of a smartphone. The bar in the center is curved so that it can also be used as a finger ring or a smartphone stand.
Considering this compactness and the price of 108 yen (tax included), this functionality is quite good. The author, who was completely comfortable, finally decided to try "Is it possible to remove it cleanly without leaving any traces of glue?" When I remove it from my smartphone ...

The paint on the smartphone case that I had originally attached has come off. And for the "card stand case", the peeled paint sticks to the adhesive surface. After just 15 minutes of trial, it's no longer usable. I'm disappointed.
If you look closely at the package, it says, "There may be some glue left when you remove it. Also, please note that the paint and stickers on the case and smartphone may come off." After all, you have to read the notes in advance. Anyway, it is a convenient product, so if you are using a case or smartphone that you do not have to worry about the paint peeling off, or if you can peel it off a little, please try it.