The Magic of the Keisei Moji (形声文字)

Natalie Hamilton is a writer, translator and lecturer in Translation Technology. She turned her focus to Japanese study while living and working in Japan’s rural Oita Prefecture on the JET Programme. She was awarded a Master of Japanese Translation in 2014, which included a linguistics dissertation entitled Cracking the ON Yomi Code. Her new kanji textbook The Kanji Code has been an Amazon Top 10 Best Seller in Phonetics and Phonics since April 2019. 



Chances are you’ve heard a lot about pictographs, ideographs and compound ideographs, but less about keisei moji – otherwise known as semasio-phonetic or form-sound kanji characters. So, it might surprise you to learn that keisei moji account for at least 80% of all kanji!

The four main types of kanji characters are pictograph, ideograph, compound ideograph and keisei moji.

  • Pictograph: A kanji that looks like what it signifies. e.g.: 木  tree, 人  person
  • Ideograph: A visual representation of a concept, often spatial. e.g. 上  up, 下  down
  • Compound ideograph: A combination of pictographs or ideographs to create a third meaning. e.g. 休 to rest (a person sitting next to a tree)
  • Keisei-moji: Characters with a radical that denotes the meaning category, and a phonetic component that denotes the sound. e.g. 訪  visit,   clear
While Japanese school students learn about keisei moji in school, non-native learners of Japanese are often unaware of them.  A lay person’s English version of the word keisei moji doesn’t even seem to exist. The dictionary term semasio-phonetic is the go-to term, and refers to the fact that these characters are made up of a combination of semantic (meaning) components and phonetic (sound) components. However, while this term may appeal to linguistics nerds, it’s not very memorable!
To find a plain English term, let’s break the kanji compound down into its constituent characters:
form, shape, appearance sound, voice character
The name tells you that these are characters in which the form, shape or appearance gives a clue to their sound. That’s why I call them form-sound characters.

How does a form-sound character work?

The radical tells you the meaning category.
Radical: (water)

Meaning category:  water-related

swim_keisei moji swim

river_keisei mojiriver

bubble_keisei moji bubble

And the phonetic tells you the pronunciation or ON reading.

Let’s look at the phonetics of the three characters listed above and the ON sounds they represent.

Phonetic ON reading
If we compare this with the kanji themselves, we can see how the phonetic is telling us the ON reading.
Kanji character Phonetic it contains Sound phonetic indicates ON reading
When we put it all together, we can see that each of these characters has a clear meaning component, the radical, and a clear sound component, the phonetic. Being able to recognize keisei moji gives you a deeper understanding of the kanji system. You’re now able to pick out the meaning and sound hints, rather than just seeing a bunch of squiggles. If you take the extra step of learning the phonetic components, you’ll be able to make an educated guess about the ON reading of a lot of kanji.
This article is an extract from The Kanji Code.
The Kanji Code provides a list of 150 phonetic components to improve your Japanese reading skills. For each component, example kanji and common words that use the corresponding ON reading are provided.
Bookmark our List of Phonetic Components so you can check phonetic components as you encounter them.


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