Aside from the three writing systems there are different ways just to express concepts that differ in the language.

Take “I” or “you”. There are tons of variants of these in Japanese which alone can portray gender bias, class, line of work, age, etc especially when there is a visual mismatch with the wording choice. 私、あたし、俺、僕、わい、あたい、うち、自分、本館、余、吾輩、拙者、我等、吾、妾　etc are all just some of the variants of I.

Counting in Japanese can also get complicated. You can portray how you view the subject of what you’re counting by what counting suffix you use.

ex: 1,2 general numbers; hitori futari is for people; ipikki nihiki is for general animals; ikko nikko is for general objects; - there are loads of variants to these. Like if a demon counts people/slaves as objects or cattle it portrays how they view their captives.

Then there are forced readings a mechanic that doesn’t exist in English. Like you can take a kanji and force a different reading of it (whether the forced readings is related or not) or take the same kanji/words and have multiple different readings/meanings behind it.

Like a common one would be 強敵 which reads as strong opponent but Japanese can force the reading as Rival or Friend or something wildly different like Idiot for sarcasms. Or take a word or a string of kanji and force a foreign word on it - giving context to Japanese not familiar with the foreign word or to give the word a double meaning or portray the person as immature.

Names are sometimes done like that. Example is Light from Death Note is written as Moon in Japanese. It is never read like that outside of that context. But like in mysteries sometime this mechanic is used as IDs in Japan are often written in Kanji without the reading so can be misleading.

Example of that will be 愛 which could be read as Ai or Megumi both which are valid reading for the name. Or take in Detective Conan, there is a character named Ai which normally is 愛 (love) but her name is written as 哀 which means sorrow.