Cause, according to this (and the lore)
Spoiler
NyxNoire wrote:Shika Mizu, water shop
midnight - 6am (adult male)
6am - noon (adult male)
noon - 6pm (adult male)
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Maza Iteiri, Herbalist shop.
Midnight - 6am
6am - noon
Noon - 6pm
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Fia Puca, Dark Shop
Midnight - 6am
6am - noon
Noon - 6pm
As you can see here, my Fia's are invisible while the Maza's are visible. In the middle of the night (it is 12:32am rn)
I think the deer are a little confused