There appear to be some kanji and other characters such as ①, ②, ③, Ⓐ, ㊄, ㊗, ㊛, ㊑, and many more, which are enclosed in circles.
These characters are listed in unicode and there are quite a lot of them, with various seemingly unrelated kanji, as well as numbers and hiragana and katakana characters.
There is also a character called 'combining enclosing circle' which appears to be intended to circle the character before it, though this doesn't work in all fonts.
Finally, in Microsoft Word, when the Japanese IME is selected, it even offers a menu option to encircle a character in your document with quite varied settings as to how to display it.
It appears that there has been a lot of effort put into making these characters accessible, and yet they don't have any clear usage that I can find, or even a mention of them at all online. Why do these exist?