How do I type Japanese characters in InDesign?

If you need a vertical text frame, and can’t use the Japanese locale, then the easiest solution is to just copy and paste one from a file that already has one. There are templates you can download from TransPacific Digital that have vertical text frames in them with the text marked with Japanese language, and the Japanese Paragraph Composer applied. If you copy and paste them into your INDD that you made in your English locale, then you’ll have a vertical text frame into which you can key your CJK text. 

These templates don’t give you access to most of the things you’d need for Good Japanese Typesetting. If you were working in the Japanese locale, then you’d have e.g. control over which kinds of characters can appear at the start or end of a line (kinsoku shori); if you’re using the template, then you have to scan the whole thing manually to make sure that you don’t have an open parenthesis at the end of a line, or a comma at the beginning of a line.  If you were the kind of person who knew all of the Japanese typesetting rules, then you’d likely be the kind of person who would want to install the full Japanese locale, with mojikumi, and kinsoku rules, and tate‑chu‑yoko, and so on.  

But, if you know what you’re doing, and you already have good multilingual typesetting infrastructure in place (you know the rules, you have the JP translator downstream from you to review your work, et cetera), then these templates are enough. Here’s a link to the TransPacific Digital downloads  - but it seems like their security cert has lapsed, and I get a warning from my browser when trying to visit the link. So, I’ve attached an IDML of their Japanese template to this post.