onyomi reading for 学
In Mandarin, this character is pronounced xué, and in Cantonese, it's pronounced hok6, so how did this character get the onyomi reading ガク?
Simplified from 學.
Middle Chinese: /ɦˠʌk̚/
Hakka (Sixian, PFS): ho̍k
etc
Korean/Hanji
학 hak
I guess the initial "ha" sounded similar to "ga" and thus became in Japanese がく.