Cautiously mind you, I find this refreshing for the moment.
The girl he left behind actually went out on her own adventuring and forging a future by herself instead of being a glorified girl next door type that never left the small town. She showed initiative (and actual self agency at that!) to be something other than a simp/haremgirl/wifu for a full fucking 6months, only chance drew her visit the MC as well! This is practically unheard of in manga trashland known as isekai.
Which is fucking rare in stories, which makes me remember there's a bunch of dudes in this too, not that they are on screen as much as the girls but close enough, they are there and do interact. There doesn't seem to be any braindead people and time actually seem to pass.
This shit got potential.