[Oh... Raidou might be on to something, actually.]

That makes sense, the more I think about it: after all, the type of spirits I used to see the most back home were Duel Spirits that were attached to cards. But this world doesn't have those cards like mine does. I have my cards here, but I haven't been able to see any of the spirits that would normally be attached to them... maybe since their cards didn't exist in this world before I got here, their spirits can't properly manifest in this place?