https://www.nanamipaper.com/pages/no-parent-page/downloads.html

reply to u/Seaborn63 at https://www.reddit.com/r/notebooks/comments/170iiax/i_like_paper_with_weird_rulings_whats_your/

Japanese notebooks can have some interesting grids in addition to the Kokyuo notebooks mentioned by others. There are a variety of grid sizes for practicing kana and kanji. You can find many by searching for Genkouyoushi as well as some with alternate gridding which is used for furigana. Some of the more sophisticated adult versions have horizontal lines which also have small hash marks for creating a sort of vertical grid for those who wish it. These are intended for those who write on the page from top to bottom rather than horizontally, but this doesn't mean they couldn't be used in other ways.

https://papress.com/products/grids-guides-black-a-notebook-for-visual-thinkers