Girl's last tour follows the protagonists Chito and Yuuri, while Chito tries to understand the world around her, and what happened in the past, Yuuri cares more about the now and rather than her brain, prefers to rely on gut feeling... as well as make sure her guts are filled.

The manga has beautiful, sketchy art that really showcases the desolate world the girls inhabit, shows dark nights - and sometimes days - cold climate, a gigantic, maze like, industrial complex that is falling apart in some places due to the lack of maintenance.

The manga has a strange pacing in which a lot of chapters seem to have considerable gaps in time between them as they find food in one chapter and in a few are already running low on it. Most of the time the girls will be using their vehicle to trek along to an uncertain destination.
While Chi takes care of the driving, repairs, cutting both of their hairs, manning the stove, reading signs, etc. Yuu just lazes on the back of the vehicle for the most part... when she isn't hurting Chi by touching a wound, cheating at games where food is at stake, (seemingly accidentally) throwing Chi's journal into a fire, outright stealing her food, etc. It makes you wonder if Chi is with her just because there isn't anyone else around.

During most of their trip they display an easygoing attitude, even when they are hurting for resources, this bundled with the fact that when they encounter some sentient being there's seemingly no interest in learning what's going on with the world, if there's a colony somewhere or anything else, makes it feel like they don't much care about what happens to them in the future. That way they meet Kanazawa - seemingly the first person they've met since they had to leave their town years ago - and soon after they're already saying goodbye.

But this happens with all of their encounters, when their vehicle breaks down, it does so near Ishii, a girl working on building an airplane to leave the city, who fixes their vehicle in exchange for the girls, or rather Chi, to help finish Ishii's airplane. Ishii soon leaves but the airplane breaks down, while Ishii is seen parachuting, she seemingly has no resources to survive, of course by this point she's already written out of the manga, so the girls simply go to their next destination after this.

This repeats with other encounters, although no more humans appear. At some point they encounter some weird life form with mushroom head that communicates through waves and tell them the end of earth is near... of course they don't ask for more information regarding this. Throughout the manga characters are introduced seemingly just to add some variety to it, and then get thrown out so we're back just to the protagonist pair.

This isn't everything that happens in the manga, it talks about humans' way of life, about how we view death, and how we find meaning in being remembered and passing down knowledge, but the way characters behave and interact seem ill-fitting for the most part.

Regarding the ending, my only problem with it is the build-up of expectation, for some reason both the mushroom heads and Chi's grandfather told them to go up... to find nothing. If they were going up just because they decided to go up, I'd have nothing to complain about, after all, there is no set path and you don't know where a road will take you, so might as well go wherever.