Try looking up han-unification and its justification and you'll see the exact opposite approach to encoding characters into unicode.

For CJK characters, they unified all semantically similar han-characters, even when they have visual forms that are quite different between Japanese, Chinese and Korean.

If you want to write Japanese and Chinese in the same document, you need to mark up the section to tell the system that renders it, to render different visual forms for similar codepoints depending on whether they are used in Japanese or Chinese.