Help remembering the name of an Anime series!?

I'm trying to remember the name of an anime series I watched a long time ago. The basic premise being that a boy is transported from a futuristic world into parallel universe in which magic exists. I can't remember much but I think the boy ends up having to go on a quest to recover a number of crystals? I remember that the boys mother ends up being from this parallel universe. A bit vague I know but it was a long time ago.