Everyone knows that kanji made in Japan is of a higher quality, sure to never break down and last you many generations. It's why I only buy kanji from Japan and not any of that knock-off Chinese kanji stuff.
I kid, I kid. But did you know that there are actually a good number Japanese-only kanji in existence? This makes sense, though. Every nation out there borrows language from some other nation. Then, they come up with some things that are their own. It's kind of like the differences between British English and American English, except only having to do with kanji. Chip chip cheerio, cowboy!
In Japanese, though, it's more interesting. Not only is it words that are different… it's kanji as well. Let's take a look at how this all went down.
Kokuji: The Creation Of New Kanji
Kokuji 国字 (national characters), are kanji that were created in Japan for the Japanese language. There aren't a ton of these considering how many kanji exist overall, but there were some things that existed only in Japan and there needed to be a way to write them. Thus, new kanji, aka kokuji, were born.
To create a new kanji isn't all that complicated, either. In fact, you or I could probably do it if we wanted (nobody would care, of course). Usually it simply involves combining kanji components or radicals to create a new kanji with a new meaning. For example:
働 = ｲ (person) + 動 (move) = "work"
込 = 辶 (road) + 入 (enter) = "crowded"
鰯 = 弱 (weak) + 魚 (fish) = "sardine" 1
I think you can probably see how the above words got their meanings. "A person in motion" is one who is working. "Entering a road" is crowded. Presumably traffic was pretty bad back in the day. "A weak fish" is a sardine. Should have been a "delicious fish" if you ask me, though sardines aren't the toughest fish in the sea. Most of the kokuji were put together in this manner. Because so many kanji had with their own meanings already been established by China, it's actually pretty easy to Voltron up new kanji like this.
But how do the readings work? Because the Japanese already had Japanese words for these kanji they were making it's only natural that kokuji would get kun'yomi readings (because kun'yomi readings = original Japanese language readings). In fact, the vast majority of kokuji only have a kun'yomi reading. After that, there are a handful of kokuji that have both on and kun readings (for example, 働 uses the reading of 動 which is どう) and a very few kokuji that only have an on'yomi (Chinese) reading for who knows what reason.
Let's take a closer look at the kokuji so you can see what I'm talking about.
The Kokuji Kanji
There are a surprising amount of kokuji out there so I'm not going to list them all out for you here. For all (or maybe just most of them) of them, check out this kokuji list or get the book Kokuji no Jiten. In this particular article, I'm only going to go over the "more common" ones for you since they're more useful, though you'll quickly see that "more common" for the most part means "not actually that common at all."
These kokuji are used fairly often. They are "common use" kokuji. It'd be understanding if you couldn't read the kanji here, because these kanji are of a somewhat higher level. If you can't read the hiragana, though, consider learning it (it's a good way to start learning Japanese).
|峠||n/a||とうげ||Mountain Pass, Climax|
|匁||n/a||もんめ||Monme (3.75 grams)|
Obviously there aren't many of them in the "common" category. This is probably because all things that are actually common probably had a kanji from China already. Definitely 込 and 働 are very useful. The others are alright too, though I think those are the two most recognizable ones. In general, though, kokuji tend to be on the more "difficult" side of the kanji spectrum in that they don't usually show up as much. Even the "common" list has kanji that kanji that isn't so common. Just imagine what happens when we look at kokuji that are "less common." Wait, you don't have to imagine, let's look right now.
"Less Common" Kokuji
There are a lot more kanji that fall within the "less common kokuji" category. These are kanji that you may not see every day, but they're common enough where they (might) be worth learning, at least some day when you're at a pretty advanced level. These are going to be things that exist in Japan but don't exist in China (or aren't common enough in China to get their own kanji). To solve this problem the Japanese created their own kanji.
|粂||n/a||くめ||(Used In Names)|
|榊||n/a||さかき||Sacred Shinto Tree|
There's some interesting items in here, I think. You get some fun insight into Japan as well. What's common in Japan that wasn't common in China? What words got their own kanji anyways even though a kanji for them already exists (喰 comes to mind)? What about non-Chinese and non-Japanese things? Japan made a kanji for kilometer, tonnage, and millimeter. The best part is the reading for these things are just キロメートル, トン, and ミリメートル. Kind of makes me laugh, but I have a poor sense of humor.
The best part about all this, though, is figuring out how these kokuji kanji were put together. For example, the word "gorge" consists of 石 (stone) and 谷 (valley). A "stone valley" is a gorge, makes sense. "Calm/Lull" consists of the 几 (table) radical and the kanji 止 (stop). I can imagine some kanji-artisan thinking about how in between earthquakes you have a nice "calm" or "lull" where the table stops shaking (and presumably you can continue your work writing down all sorts of made up kanji). Because kokuji are purely meaning based (no on'yomi to worry about most of the time, so no kanji components taht are there solely for the reading) it's particularly easy to break apart a kanji and figure out where it gets its meaning from.
Go ahead and give it a try and share your favorites in the comments. It's interesting the treasures that you'll find.
Uncommon kokuji are just that… uncommon. They don't fall within the joyo kanji… or really anything close to the joyo kanji. This is the kind of kanji you learn when you're a giant kanji nerd hoping to pass the highest levels of the Kanji Kentei test. There are even kanji in here that go beyond that. It's honestly pretty nuts.
That being said, there are also a lot of them. Most kokuji kanji fall into the "uncommon" category. Out of just under 400 kokuji kanji, maybe 50 are worth learning… maybe. It's interesting stuff, but not something I'd waste my time on if you have more useful kanji to learn.
If you are interested in the uncommon kokuji though, they're on this kokuji list. You'll want to find things in １級 (first class) or 範囲外 ("outside the [test] range"). Basically, even if you know 3,000 kanji, it won't be enough to know all these particular kanji. The Uncommon Kokuji list falls somewhere between kanji numbers 3,000 and 6,000 (and possibly beyond). If you decide to jump down this 兎 hole… good luck. You'll need it.
Evolving, Changing, Adding…
It's a language, after all, so it's going to change. The cool thing about Japanese is that when you create a new kanji you're really creating a new piece of art. It's not just a new word with a new combination of letters like in English (fabulicious!), though the idea is the same.
Kokuji has been around for a while, too. The first mention of a kokuji kanji was in the Manyoushuu, which was written around 759AD. So, the first "Japanese-only" kanji was created sometime before that, which is a while ago. The most recent official kokuji created was during the Meiji Era. Because this was an era of modernization for Japan, there were many new science and technology things were getting introduced to the country. You can see this in the list above where kilometers, tonnage, and millimeters have their own kanji.
In fact, some of these kanji even got imported into China. The kanji 腺 is one such example. It's kind of funny to me how originally kanji got imported into Japan from China but now some kokuji has made its way back. It's nice to share, I guess.
But, now I wonder if we'll see new kokuji in the future. I really want to, but katakana will probably prevent that from ever happening. Kilometer is written in katakana now. Things that are common enough to get their own kanji these days probably already have a kanji. Perhaps there will be some great new discovery in Japan in the future, but I doubt it. Even something like that would probably just get named using multiple kanji in the form of a jukugo (multi-kanji) word.
No, my only hope for new kokuji is an alien invasion / visitation. It will have to be something that introduces new things to the world like which we've never seen. Even then, most people will probably just create jukugo words… but there's a chance… a hope! And perhaps, thousands of years from now, when the aliens are all gone, people will look at these new kokuji kanji and hypothesize that ancient aliens once visited our earth.