As @builderofcastles said, both Japanese and Chinese can be written vertically. Korean can too, as well as Mongolian and Manchu. There may be others but I'm far from an expert.
It doesn't really change things. All is the same, just different orientation. Newspapers are generally printed vertically, and the daily haiku with them, often in one line, the same as if it were horizontal.
Oh wow, that is cool.