I know this game is designed for girls, but, I'm a man, and I'm a grown up, and why I'm playing this? It's my way to have my own decisions to play anything. I using the DeSmuME emulator, but, what I should to rip these models such like characters (including the face and body parts), clothing, etc.?
Dude, you never have to justify your gaming choices. Play what makes you happy, end of discussion.
Now, as for ripping from DS games in general, there is a t
utorial here on the VGResource, and from the looks of it
MelonRipper is also an option.
J-Red's Github has a bunch more info, too, but each game is going to be different/have different formats so this is all general info. Give 'em a look, give 'em a try, poke around a bit, because the best way to learn (in this and many things) is by doing the thing. Good luck!