Japanese documentation is quite different for many reasons. Aside from its departure from the standard 26-letter alphabet, its encoding means that you’d have to deal with logographic character “embedding” in a screen space that is double that which you are typically used to. As such, using Kami with these documents may take a bit more than your usual method, so here are a few tips to get your work efficiently through:
Handwritten Japanese should be manually marked. It’s enough that the character system is already complex, but when dealing with handwritten versions of the stuff, things can just get far more complicated. To bypass this would-be problem, the handwritten text needs to be manually marked first. Annotate the image text with a comment (with the legible Japanese version or the translation itself), with the comment marker itself placed just outside the phrase or clause. If there are multiple comments needed for separate words that are clumped together, then it might be more efficient to simply extend the comment itself to accommodate the highlighted data (as opposed to making several comment bubbles, which is most likely impossible because of the default marker size).
Use Furigana whenever appropriate. The best thing about editing documents with Kami is that inputting text feels far more intuitive than an ordinary word processor because of the freedom you have with positioning. In Japanese documents, this might be best used when dealing with Furigana, the small Kana text placed on Kanji letters to denote its pronunciation. The drill is simple: just use the Text tool to write the Furigana above any Kanji text in the document where it would be needed. You can even sprinkle the Furigana text with any color that you may want. Take note, this tip would, of course, make use of your OS’s IME settings, which is presumably already Japanese text-ready.
Keep proper note of specialized terminologies The astonishing thing about Kanji, the third character system in Japanese writing, is that users can directly ‘invent’ unique terms by properly mixing and matching the needed Kanji. This writing method is mostly used in fictional works and materials such as novels and is the perfect way to show a new thing while almost instantly explaining what it is (through the letter’s symbolic meaning). If you ever find yourself editing a Japanese document with these terms, then it is important to take note of it by highlighting, by encircling, or via annotation. The explanation can be a small description regarding how the word is formed or its purpose (if used in literature). Alternatively, a standard word mark may also be used whenever the same word pops up in the document for note keeping.
Finally, if you are using the Japanese document as an exercise (for teachers) or study material (for students), then it may be appropriate just to plaster the entire document with annotations regardless, at least in accordance to the document’s target fluency level. It may seem tedious and redundant, but it can potentially save a whole lot of time compared to repeatedly looking at a different note constantly.