Thank you for translating "Existentialism: The Manga". It may sound like I'm joking about being thankful, but I'm not.
Let's roll through this here. The choice was nothing but random. You ought to simply accept that "it happened". Hardcore basic foundations of existentialism. Things exist. People exist. There doesn't have to be a greater reason or purpose behind it. Literally the foundations of existentialism.
"He's saying something and meaning nothing at the same time..." Kind of the whole point of it. Nothing is inherently meaningful. You choose to attach meaning to things. People, humans, choose to attach meaning to things. I'm stepping aside from the manga for a moment and saying that's not a bad thing, though. A human chooses to care for their offspring because that's important to them. It's a choice, but that doesn't make it a bad thing. That last part is not in the manga, but I felt I needed to say it because existentialism is not nihilism.
I'm writing as I'm reading, but I've said it before, and I'll say it again. The pacing in this story is so weird. It puts into one single chapter multiple very different stories. I mean, that could be a reference to exestentialist thought like A Thousand Plateaus, but I really don't think that's the case here.
Regarding the units to count mountains, to anyone who doesn't know (obviously the translator does), it's related to classifier words. In some languages (Japanese is one), in order to count something, you need a classifier word. For example, in English, you don't say I want one mud. You would say I want one bucket of mud, one jar of mud, one something of mud. The something is a classifier. In Japanese and other languages, basically every thing is like that. You use different classifiers for different objects because that's how the language is arranged. For example, you would use one classifier for humans and human-like stuff and a different classifier for paper or food.
And lastly, my own thought, is Kurihara suddenly becoming a main character? That's kind of a weird turn. I'll wait and see.