I think it is Girls' Last Tour's parody. Correct me if I'm wrong. The setting of that doujin is 1 black hair girl and 1 blonde hair girl living in the ruined city. One day they found an alien machine, somehow, the story flows to NSFW scene where we-all-know-what-they-doing. In the very end, we see a bunch of kids, which I guess that machine helps them make the new generation by **** act.

It was very sad that I don't remember the title. But I believe that I've read somewhere. The art looks quite mature, nice, tidy. So I hope somebody could me find the title of that doujin.

I swear the setting is parody Girls' Last Tour... Weird... Thing likes a dream...

last edited at May 5, 2018 12:24PM

It's not doujin, it's from the Yuri Ninshin commercial anthology series.

https://dynasty-scans.com/chapters/i_want_to_leave_behind_a_miraculous_love

By the way, there's a "What's that manga called?" thread.

last edited at May 5, 2018 12:31PM

Maybe this one

Oh, thanks guy. No wonder why I misunderstood it with Girls' Last Tour. They are way alike in the characters.