Looking at his design, I really wonder how the rings will come into play. The fingers in the belt don't seem like they're going to get rings... There doesn't seem to be any docking area there or anything, just the hand, so will they really attempt to sell actual plastic rings for boys' fingers? How can that work considering how quickly a child grows? It'd be pretty hard to make rings that fit different children's hands...
Unless, maybe the hand is just a cover and the belt opens up to insert the collectibles inside it. In that case, the rings on his hand are likely just part of each form's design, rather than collectibles or anything like that.
Edi: The scanning idea also could work, I guess, but I'm not sure a scan would be very practical for a 5 gimmick in this case, considering how you'd have to pass one ring at a time, rather than loading them in a belt and then passing a scan through them like with OOO.
Edit 2: I've just seen the actual update on Henshin Justice. So, it is a ring scanner. I guess that confirms no 5 gimmick. He just scans one ring to transform and different ones for a specific abilities.