I have no idea why the author wrote this message, but it looks ridiculous. He/she deliberately ignores the fact that "foreigners" don't know Korean. It is obvious that "foreigners" know about this manga only because of the translation.
This manga is meh. The fact that mc was a hero doesn't affect anything (a few flashbacks is all what you get); he completely ignores all his previous life experience. And even the slice of life part of the story is bad. Don't waste your time on this piece of terrible writing.