Yuumi and Bard Related

In Bard's video it seems that the old man running up the mountain holds a magical sphere of some kind,or "the stone",as the warrior calls it in the video.When he hardly lingers to life,waiting for bard to come and take the the sphere,we get to see it up close for the first time...It's exactly the same shape and colour of the shield that Yuumi puts on an ally if she has activated her passive.Could that mean that they are somehow related?Not necessarily master and cat,but casters of the same magical art...