Well, I'm gonna review the wiiware version even though this is the DS version. Ok, so there isn't much to worry about language wise, a few hells and dam**t's. Then, also, pretty much all of the woman in the game are like what you would find in a japanese T-rated game. All of them are supper skinny, and most of them have very low-cut shirts. Also, there are some who use their prettiness against other players. There is blood.
I would trust a pre-teen girl to play this, but because of the... um... not so modest woman in the game, I suggest waiting for the a 14th birthday for a guy.