If you have pictures of a 13 year old girl nude, that's considered child pornography.
They do NOT have to be doing any sexual activities.
The Sentinel class looks like a child, and even if there weren't any laws about it, MANY people would be really uncomfortable if they see a nude child in a game like this.
There are many games that have been censored due to this.
You know it's funny how people suddenly assume with what happened with Tera Online that every single game has to be censored, including any art-form or product. This is not the case and can be (and has been) proven a variety of times ranging with different products and artists under licensing companies in North America. Even titles like "In the Night Kitchen", "Blundering Angel Dokuru-Chan", Vampire Bund, Chobits, ect.
What censoring stems from is a misunderstanding and fear of the entertainment culture and expression around video-games and artwork. I've met with asian people and spoken with them, some of them have become my good friends. It's pretty normal that they have commercials or female-singing groups that have cute, flashy outfits in them as part of the pop-culture, or food being cutesiefied. And there is nothing wrong with how their entertainment is, as it is just a form of entertainment and expression and nothing more. Unfortunately the gaming stigma on 'mainstream gaming' NA seems less of a "melting pot"(i've seen more variety in a bookstore quiet honestly) and less diverse than anything else. I've seen some players(and non-players) really go out the way to almost in a sense condemn those who either
1) Are Asian(Phil Fish anyone?)
2) Like asian-type games or entertainment
Most of the time these types don't even have a clue(or don't care) what the culture or fandom is when they do this. None of them really watch anime at all, or assume that everything is terrible or video-games are connected to real-life based on their own religious standards. Or that fans are devils because they uh, play video-games and watch animated shows that they don't, therefore they must be some sort of vile creeps. Which is not true (consider Ryan Matheson, a pretty normal guy and geek who just likes anime entertainment as a hobby and a fan, and stood up for it too).
Basically there's two ways companies do stuff generally:
1) Companies that stick to their guns of their product
2) Others that make changes/censor
While I can see how some companies want to stay more on the mainstream-'acceptance' side of what gaming is standardized 'to be' and nothing else,it is ironic that SevenCore Online is uncensored(Amani Race) and has the same pixel clothes that got censored on Tera (Elins) and Scarlet Blade (Sentile). Now how is it possible that SevenCore Online, a game already released in english in North America can have uncensored succubus outfits with garter-belts, but all these other recent 18+ korean games are getting censored left and right for well, the same stuff.
But what I do find it saddening that people are more worried about sentiles or what-other race, or class, or pixel, or an art-style because something looks cute(game characters with lines, big-eyes, doll-headed, mesh-wiring and coloring inside a computer program, not flesh and blood like a real human being) is automatically real-life "child" rather than what is really a typical bishojou type character in a video-game (which is called "moe" style). Yet abortion is pardon and excused but condemned/illegal in korea. Abortion the actual killing and harm of children human-beings(real life) is pardon as a right, but condemn the pixels if someone decides runs around in their undies on a fantasy game that they wanted to play.
Since Scarlet Blade came from Queen's Blade and with the censoring that's going on now I won't be surprise if more is eventually taken out (there are full nude mini games of the other races) and gets turned into a 12+ game.