This notebook (and brand) is ubiquitous and utilitarian in Japan, but not in the US. I'd like to think that this notebook is similar to how someone who grew up in the US might think about standard Mead spiral notebooks. They're incredibly cheap, available at basically every store, and you go through dozens of them while in school. They're not the most robust notebooks, but you can't beat the price! It's this utilitarian and minimalist design that I really like about this notebook, and it's also whey I always have one going in some way or another around my desk. If you haven't checked these out and could use a great "throw-around" notebook, the Apica Blank Twin Ring A5 notebook is a fantastic option.
If A4 isn't your thing, you can also pick these up in semi-B5.
(JetPens provided this product at no charge to The Pen Addict for review purposes.)