Isn't most if not all technology in the underworld powered by magic? Because if so, that collar would basically be just a necklace if he used his ring. On that note, why does he never use his ring to defend himself. Not a single demon border patrol officer would be able to so much as touch him...
I would still destroy that shrine if I was him as long as it wouldn’t destroy them. Because fuck that test shit, what stops them from resealing the tails on a whim
If say… the temple is destroyed, will the spirit inside be destroyed? Because if not I would’ve smashed that tiny box the moment they left. In most lore of yokai, they can find new homes before disappearing