Saturday, 7 March 2020
In Japanese, ///, three slashes or more, may mean someone is blushing, red-faced, probably embarassed. For example:
Don't look [at me]. *blushes*
Naturally, this originates in the parallel diagonal lines used in manga to render blushes. See blushing lines for details.
Anime: Gekkan Shoujo Nozaki-kun 月刊少女野崎くん (Episode 1)
These slashes may also appear in manga text balloons when the character that is talking isn't visible in the panel where their text balloon appears.