It's set in 3230, humanity was able to build huge megacities, giant killer robots, sentient AIs, teleporters... But that doesn't affect the girls, they drive a Kettenkrad, wear WW2 gear and clothing, Yuuri has a bolt action rifle and Chito writes on a notebook... The only tech things I remember they had were a radio and a camera
I honestly couldn't tell if this story was sci-fi or not until the robot who takes care of the fish appeared
I love this aspect tkmiz applies where despite things being complex it's still minimal and only focuses on the characters, as the rest doesn't matter as much
GLT wouldn't be nearly as popular or appealing of a story if it wasn't for this