Kanji is a puzzle, you just need to learn the pieces
Many kanji have two or more readings that need to be learned in addition to their meanings. By learning the phonetic components of kanji, this task can be made a lot easier. If you don’t like rote learning, you will love the phonetic components.
Most people know about the radicals, the part of a kanji character that indicates its meaning or meaning category. For example, the radical in forest 森 is tree 木. But not everyone knows about the phonetic components. They are the other side of the same coin, but instead of giving a hint to the meaning, they give a hint to the reading or pronunciation – specifically, the ON (Chinese) reading.
For example, the phonetic SEI 青 appears in the characters for clear 清, ask 請 and spirit 精, and they all have an ON reading of SEI.
If you can access a list of phonetic components and memorize them, reading kanji becomes a systematic process of recall, rather than a stab in the dark.
Phonetic components appear in keisei moji (形声文字) or form-sound kanji characters, which make up 80% of the Joyo or daily use kanji. These characters contain a radical that indicates the meaning, and a phonetic component that indicates the ON reading.
A list of 150 phonetic components can be found in The Kanji Code, a new Japanese textbook.