The forgotten rose (Diabolik lovers ff)

Lumina is a girl who was found unconscious by some villagers at a river. A couple took her in, named her Lumina since no one knew her real name, and they became like her real daughter, whom they loved very much. However, no one, not even Lumina herself, knew what had happened to her. But they didn't really care about that.
When her parents have to travel for family reasons, they leave her reluctantly with the sons of an old friend. Who would have thought that this would lead her to rediscover her forgotten past...