Here are my Maruman notebooks in wide and college rule. They’re A4 for more room, a size that fits an average laptop bag. Plus if you get off on adhering to non-US standards, there you go.
Every page tears out, so when I rewrite something I can trash the old draft. That way when I’m at the end of a notebook I’m not leafing through all my old stuff in case I forgot to transcribe something. Without scrapping my old stuff, I wouldn’t have written half the things I’ve put in these notebooks. Save the curation of your past for your fans.
In San Francisco, you can get these notebooks at the fourth-floor Mai Do stationery store in the Westfield Mall. The store sells lots of Japanese trinkets; when I picked up four Marumans yesterday I grabbed some incense, chopsticks and tiny origami paper (because holy hell it was under two bucks for 500 sheets and I could make enough itty-bitty cranes to get me halfway to a wish).