High school dxd: the moonlit neko

Kuroka was always without her sister in her life. All she knew Is that she had one, but now her sister is missing. Where has she gone? The only clue she gets is a locket with a picture of her sister inside. She sets off on an adventure with her friend aiden, to make sure her sister is found safe. Throughout the whole story the one note she finds is the only clue to find her sister.its a riddle that consists of life and death. Will she solve the mysterious riddle? Will she find her sister? Or will she fall into the trap of a red rose gone black? Find out in the moonlit neko