Sister's Secrecy: Arcanum Bloodlines

For as long as humanity existed, there has been an ancient order which prevented the dark forces from taking over the world. The order's name might have changed as the centuries wore on, but its essence remained the same. They were called "guardians," and our story is about the kids of one particular guardian. One day, fearing for their lives, he left his kids at the doorstep of an orphanage on the other side of the world. This is where our story begins...

Source: The Publisher Website.