Shiori

Shiori would had spent her playful childhood days in a very calm and unique island where only children live and from time to time, a mysterious man would come to check on everyone. The kids there never gave the man much attention since he would usually just watch from afar and the children would not even notice when he was gone but, on one of his visits, he came to talk to Shiori and to this day she can't clearly remember what he said to her but on that day, away from her friends, the man took out a blade shaped out like a key and pointed it to Shiori's chest. She fully understands it now that was the moment the mysterious man opened her heart to the darkness and without any way to protect herself, Shiori being was swallowed by the darkness. As her "transformation" ended, the man was surprised by all the power she had in her heart, a powerful dark blade appeared in her left hand and so Shiori became his puppet.

For quite some time Shiori followed his orders but it was like she was seeing through the eyes of another person, she felt small, powerless and hopeless, she believed to be her fate to live like that for the rest of her life until one day, her orders demanded Shiori to go back to the island she grew up and choose one of her long lost friends with a heart powerful enough to be the new puppet. Shiori shivered to think about doing with anyone of her friends the same thing she went through and as all the children in the village came to her, happy to finally be seeing Shiori again, Shiori wished from whatever was left of her heart to be able to fight the orders of that man back! She never wanted to hurt anyone and she specially didn't want her beloved friends to suffer, for what is worth, she wanted to take the control of her body back from the clutches of darkness! And for a miracle, the faint light that still remained inside her shone bright giving her even more power and so, Shiori was able to stop herself from hurting anyone! 

Of course, Shiori would never be able to go back to what she was, as now she knew about light and darkness but she accepted herself as she was, a perfect balance of those two elements, with both the blade of light, in her right hand, and the blade of darkness in her left. She will always remember the wrong things she did while the man was in control but as a kind of atonement, Shiori decided to be the protector of the island, so that man would never be able to steal another child from there.