Is it usual in anime/manga/japanese to use ブツ as onomatopoeia of mumbling?


In My Hero Academia we see that when Midoriya is mumbling they use ブツ to
symbolize it. Is this the rule for anime/manga/japanese or does it only happen
in My Hero Academia?

[![enter image description
here](https://i.stack.imgur.com/e6dlc.jpg)](https://i.stack.imgur.com/e6dlc.jpg)




ブツブツ or ぶつぶつ (the same word, just in katakana vs hiragana) is a standard
Japanese onomatopoeia for mumbling, muttering, or grumbling to oneself. [This
list of Japanese onomatopoeia](https://www.nihongomaster.com/blog/japanese-
onomatopoeia-guide/) includes ぶつぶつ in it, along with many other onomatopoeia
that show up in manga.




ブツブツ or ぶつぶつ (the same word, just in katakana vs hiragana) is a standard
Japanese onomatopoeia for mumbling, muttering, or grumbling to oneself. [This
list of Japanese onomatopoeia](https://www.nihongomaster.com/blog/japanese-
onomatopoeia-guide/) includes ぶつぶつ in it, along with many other onomatopoeia
that show up in manga.

