Prologue:

Serena is the oldest of 4 children. When she was 4 her twin sister was kidnapped and still continues to be missing. Luckily for her she had her best friend Jessica there to help her through it and help her come up with a plan to search and find her. On the night of the 12th anniversary of her twin's disappearance fate struck again. Just as her and her best friend were nearing and about to finish their last mission things took a sharp turn for the worse.
Now her best friend is thought to be dead as well, but Serena doesn't buy that one bit. Now she plans on going to Shibusen, just like her parents did, in hopes that she might be able to find the whereabouts of the witch that took both her twin and best friend.