The manga Kris is reading is called Neko Jump, but there's a little more to it than "what if Shounen Jump but cats." One of, if not the earliest example of Japanese comics being published outside of Japan was a magazine called The Japan Punch. Fast forward to today, and there is an actual, though sadly Japan-exclusive magazine dedicated to cat manga called Neko Panchi or Neko Punch. "Neko Jump" is a Neko Punch-esque play on Shounen Jump... and, yeah, what if Shounen Jump but cats.
And yes, original Japanese issues of Shounen Jump really are that massive. The tradeoff is the paper and print quality aren't great. Neko Panchi is also pretty thick and the paper and print quality are better, but they're only the size of mass market paperback novels.
Humorous, though only vaguely related anecdote: a prominent figure in manga history was a Frenchman named Georges Bigot - pronounced like "Big O" - who I mistakenly thought was the founder of The Japan Punch until I double checked and found that was an Englishman named Charles Wirgman. Anyway, when I was taking my manga history class... wow, ten years ago? the teacher mentioned trying to find pictures of Georges Bigot on Google only to keep getting pictures of George W. Bush, and being very confused for a minute.
Even further off topic, I was strangely obsessed with the Main Table theme of Dragon's Fury (the Genesis version of Devil's Crush) during the coloring process. I guess it's because I got a PC Engine Mini from Japanese Amazon, wondered why it had Alien Crush instead of Devil's Crush when pretty much everybody agrees the latter is better, and one thing led to another.