As a fluent Japanese speaker, I’ll give you context. Nearly all of Kanji and many words in the Japanese language have Chinese roots (in fact Kanji itself means “Han Chinese letter” in a literal sense). Of course many characters are variants when compared to Traditional or Simplified Chinese, and in terms of complexity, Japanese Kanji sits between the two.

In speaking, there are two categories of reading characters onyomi and kunyomi. Kunyomi is the unique Japanese way of saying things, and onyomi is saying a word in a way derived from Chinese. Telephone is 電話denwa in Japanese vs. 电话 dianhua in Mandarin, Society is 社会 shakai in Japanese vs. 社会 shehui in Mandarin. See how they line up closely?

Now, the question is when do you use which? As a general rule of thumb, when multiple are combined together, you use the onyomi (Chinese-derived way like the above examples). When by itself (many exceptions apply) or when followed by hiragana letters (which is called okurigana) as part of the same word, then you use the kunyomi. I’m not going to complicate things further on this topic unless anyone has questions about something they wanna know more specifically.

Prepositions and connector words in English (and, is, have, to, with, not, do, will, you get the idea) use hiragana only.

Borrowed words from foreign languages use katakana almost exclusively. Bear in mind that not everything came from English, so just putting English words with a lot of extra vowels is not sufficient to make a coherent Japanese sentence. パン (pan is from the Portuguese word for bread), and ピーマン (pi- man is from piment, the French word for pepper).

Japanese people kept kanji around because the letters give a descriptive meaning when read as written and helps reduce confusion when many words can sound similar. This was also the case for Korean (kanji is known as Hanja) and in other languages if you go back further in history, but it has largely fallen out of favour in modern times for those languages.

I’m happy to answer any followup questions about this for my fellow lemmings.

People always seem confused about the redundancy of having Hiragana/Katakana when they both mean essentially the same thing.

But then I point out that we have Upper/Lower case letters.

This blog and the Wikipedia are good starting points. I don’t speak Japanese, but I do speak Chinese and have a background in linguistics so am peripherally aware of what’s going on so take that with as much salt as you need.

It’s useful to note that there were multiple attempts to go the “Oops! All kana” route or use romaji, but for a variety of reasons cultural, political, and linguistic, those didn’t pan out. Writing systems are deeply informed by a specific historical and social context, and what at first seems like irregularity or unneeded complexity, are often actually the traces of that history marked on the language.

As for issues like why katakana is used for non-foreign words too, I thinks it’s best to think of language feature less as strict rule followers and more like a species in its ecological niche. Katakana is very good at rendering foreign words in Japanese, but if it finds some unfilled gap that isn’t being better filled by some other feature people will use it to to fill that gap too. When the semicolon was developed in English no one imagined at the time we’d use it to do this ;-) but here we are.

As someone who reads Japanese, reading all kana can be slow because you are reading one syllable at a time. It makes going back to old video games and reading children’s media tedious.

Once you know enough kanji though, you can read incredibly fast. Depending on the material, I can speedread faster in Japanese than I can in English.

This is because kanji is meant to be recognized at a glance rather than read in your head. The kana in Japanese sentence is supposed to provide grammatical context. So instead of reading “Inu ga ie ni nemashita” in my head, I’m seeing “Dog, in house, slept” from a glance.

So the downside to this system is that you’re spending most of your education learning every character you’ll need, but the upside is it can make reading very efficient once you have got it down. I think it’s part of the reason Japan still has a pretty robust book culture.

Because the Japanese. That’s the snarky but concise answer.

The longer answer is for lack of better term, “social stubborness”. The Japanese way of doing things is to push ahead even if it is too difficult or irrational and very rarely to admit mistakes or retreat. The Chinese way of writing is already cumbersome and lossy. The Japanese partially adopted this script and then shoehorned their own homebrews to power through the deficiencies. I hope one day the Japanese do a proper writing script rationalization to get rid of this…abomination.

These three systems basically formed a Voltron of language if you will. Hiragana is commonly used to make up most of the sentence structure, katakana is commonly used for foreign words, and Kanji is most commonly used for nouns.

With their powers combined they make up sentences. As for the why, it largely has to do with tradition and history. Korean has shifted to a more easy to read/understand writing system, but in Japan it is much harder to do something like read a newspaper. Why? Because you either know the Kanji or you don’t. There is no sounding it out.

There are lots of exceptions to when to use certain writing systems. For example, sushi can be written like 送信, すし, or スシ in advertisements. I asked a Japanese friend about it and he basically said it just depends.

PAIN

All joking aside, Katakana and Hiragana are a bit like having lower case and uppercase letters, Kanji is like having symbols for specific things, like the save icon means “Save a file”