It's tagged "side-tie panties", correct me if I'm wrong but I thought that the string was for tying the front and back "flaps" together and are not part of her panties at all.
If only, This is why only a few people can cosplay DoA The ample breasts, Im not saying she´s a bad cosplayer, quiote the contrary, she´s lovely! Kasumi just loses her charm without her boobs -at least that´s MY opinion