Hobonichi Lined Notebook - A5 SizeNotebook Details This A5 size notebook has thin and sturdy Tomoe River paper and opens flat. This all new notebook is based on design psychology and reduces eye strain. The notebook is 10mm thick and contains 288 pages so you can write as much as you want in a single book. It's the same size as the techo, so it can fit into a techo cover. The notebook size is the same as the A5 Cousin, which makes it compatible with any of the Cousins Hobonichi Techo