Vivarium de Choushoku o - Vol. 2 Ch. 17 - Hardening Capture Goo

[MangaDex]

 

[UnvalidUserName]

I'm getting the feeling that they are not "from the future", it's just this town some sort of experiment were they keep people isolated, thinking they are living in centuries past. Like a Truman's Show of sorts.
It would also fit with the title being about a "Vivarium". A human vivarium to be specific.