Recently, on the repeated advice of a few of my friends, I started reading Yokohama Kaidashi Kikou
(OneManga page for this manga, which has never been licensed), which is best described as "Post-apocalyptic slice-of-life". Despite being post-apocalyptic, it's not depressing or sad at all, really. In all honestly, the feeling it evokes is like what Calvin and Hobbes or Yotsuba& does, in that a lot of things that helped set up this world you're in are mysteries, and are kept mysteries simply because they never enter the scope of the story. The art is also kinda cool. The backgrounds are really lush and well done, and the characters are all pretty distinct. It's not hard to tell one character from another just by looking, and you're not flipping around, trying to figure out who that guy was. However, a bit early on, the look like they were designed by that drunk ZUN, but they get better as time goes on.