四 is yotsu that i understand but why 谷 is “ya” non of the readings of 谷 is “ya” i don’t get it
や is actually one of the nanori, which are readings that are used only in names, though it’s historically a kun’yomi.
It’s also got the same reading in 渋谷, 世田谷, and 谷中, which are all locations in Tokyo.
I was gonna mention 谷地 (やち marshland), but upon further inspection, it appears to be ateji for an Ainu language word.
guess its something you just have to learn by memorizing over time per case,thanks