Kun'yomi are characterized by the strict (C)V syllable structure of Japanese words (yamato kotoba).
In a number of cases, multiple kanji were assigned to cover a single Japanese word.
For instance, the word なおす, naosu, when written 治す, means "to heal an illness or sickness".
As a result, native speakers of the language may have trouble knowing which kanji to use and resort to personal preference or by writing the word in hiragana.
承る uketamawaru, 志 kokorozashi, and 詔 mikotonori have five syllables represented by a single kanji, the longest readings in the jōyō character set.