The Key

This is the special key that opens the lock to Diva's cell in the tower. It is made of gold and is highly ornated with an intricate design. It is kept under Joel's custody with his other valuable items. But Saya finds it out and manages to procure it when Joel is absent from his study. She uses it on his 72nd birthday to open the lock of the cell and frees Diva to let her come out and sing. But that incident starts the feud between the sisters.