I work a lot with Japanese texts and this would be my request feature number 1.
When you are writing in horizontal, you can change your selected text to vertical orientation. (When I tried , that bar didn't flip from horizontal to vertical.)
Like this example: (カレー).
(This is wrong writing) x (This is acceptable)
x ー > |
That also works inside Text Editor for mac, when you go to Layout Orientation > Vertical.
My other suggestion is to add something like World and iPages that is called > Phonetic Guide Text. (It's used for both Japanese and Chinese called Furigana or Ruby)
Japanese Indesign has all these features for writing in Japanese too.