Ow god, I jumped when I saw the photo of Mannie Dex inside the shop from Mannie Chex!
If you don't know, the Mannie is a family of merchants. It first appeared in The Lost Random from 2021 with Mannie Dex, witch sells Cards to use during the game, and Mannie Chex is the merchant inside the Black Die, where "The Eternal Die" takes place.

Here is a little discussion from "Antti / The Eternal Die dev team" talking about this easter egg:

"The Mannie Family is a very market-sensitive breed of Merchants and just because they can be everywhere, it doesn't mean it would be profitably reasonable for Mannie Dex to appear in the Black Die and cater to Aleksandra. His goods would simply not match her needs. Supply and demand, and so on. Mannie Chex, on the other hand, has just the right supplies to offer..."

And here is the link: https://steamcommunity.com/app/2564520/discussions/0/591764421283454995/

That was a nice touch from the devs, and after I saw the story, I love it =D
I wish we could have a card with his face, or even an item that represents the family, which will be nice too. =D