More precisely, newspapers, most books (except technical/scientific ones) and magazines are written in the vertical form. Comics too. Business documents are typically all horizontal.

Also they have a uber-complex w3c standard (draft) to support this system: https://w3c.github.io/jlreq/#vertical_writing_mode_and_horiz...

Why past tense? Traditional Chinese is still written this way in Taiwan and I think to a degree Hong Kong. I purchased a copy of Three-Body Problem typeset this way while staying in Taiwan three or so years ago.

Relatedly, the TB-RL[0] system leads to some fun confusing cases for beginner learners, where in the city you may see signs for cafes or restaurants with text apparently written horizontally, but backwards. In fact, it’s just like the vertical signs on sides of buildings in the US, but in this case the sign uses TB-RL: each letter is on a new line, and lines go right to left.

[0] Top-to-bottom, right-to-left.