Wow, I'm actually kind of curious now about the Korean rating system. :0
From what I understand, Korea's rating system works like PEGI - they have the age rating and then on the back there's little symbols detailing how the game earns its rating.
On this game's box they have a little text box with quotation marks. Maybe it has something to do with the reading level required to play and understand the game, or obscenities in the game's dialogue?
or maybe they're trying to indirectly force the game to have an older fanbase? i dunno lol