Hello
I'll fully admit that, except perhaps the whole geopolitical drama going on at the moment, I'm quite ignorant about Korean culture. I never would run a game set in Korea...
... but this thread is still a goldmine. Variety is the spice of life, and having an adventure strongly incorporating aspects from a different culture can work really well. For example, some important mystical do-dad (the First iron spike?) is being displayed in a museum in your home town, and Korean bad guys want to steal it, a Korean good guy shows up and is asking the locals (ie the PCs) for help... There are all sorts of ways that different cultures can be used to change things up for an adventure or three. The player's lack of familiarity with the foreign mythology can add a level of tension - the "bad guys" want to use the First Spike - is that actually a bad thing? etc.
A lot of immigrants live in large Canadian cities, so this could be another way that non-european cultures and mythology could be incorporated in a campaign.