Bad Luck Charms (a.k.a a Prolouge)

Two girls and a cat are dropped into One Piece very early on, with different magical objects and some used powers to get through the hell of the world called One Piece. They meet some of the main people and try their best to change some horrible past for the better, while trying to keep the original plot as best they can. Nothing's perfect, though, with them being teenage girls and having way to much high tech on them, you can bet they will have their screw ups and great achievements.