Well I can only speak to my experience, and my experience has been that manga is fairly popular among people around my age and younger, but still far from ubiquitous. I still regularly have to explain what manga is to people my age and especially those older than myself.

Regarding kpop, the fact that my phone’s keyboard doesn’t recognize the word and the fact that I’ve never heard a kpop song on the radio much less any sort of radio station dedicated to it I feel kinda demonstrates that it’s still pretty far from mainstream.

“Manga” is the Japanese word for basically “comic”. In the English speaking communities it generally refers to Japanese comics where the primary difference is that the panels are generally read right to left whereas the text inside (if it’s been translated) is usually read in our typical left to right.

There’s more cultural differences largely stemming from how in the West (or at least my experience here in America) comics were often considered for kids or niche nerd communities, whereas in Japan it’s been more acceptable for a wider audience to read them for a longer time, but webcomics have been making the medium more accessible and thereby more acceptable for wider audiences so that stigma has been slowly being diminished.