A large thing here is that Wanikani is teaching kanji as concepts. When you get the vocabulary that is when you are learning actual Japanese words. Usually you tend to learn the onyomi reading with kanji.
On’Yomi translates directly to mean “Sound reading.” This refers to the Chinese reading of the kanji, i.e. the original sounds that they make in the Chinese language. Of course, the Japanese and Chinese languages are very different, which means the sounds that Japan gave to these kanji are really just close approximations of the original Chinese pronunciation.
The vocab utilizes kunyomi generally.
Kun’yomi, on the other hand, is the Japanese reading of kanji. This, as you can imagine, is Japan’s (pretty successful) attempt at making their language work with kanji, that way they wouldn’t have to learn Chinese to read everything. A Chinese kanji’s meaning (not to be confused with pronunciation) would be taken, and a close Japanese equivalent word to that meaning would get associated with it.
Since we are learning Japanese, there’s really no reason for Wanikani to teach Chinese readings to us unless it’s that word in the vocab anyways.
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