Chinese characters (In Japan they referred to as Kanji), are ideographic rather than phonetic.

This means they represent an idea (or concept?) instead of a sound. The meaning is completely divorced from the pronunciation. In Japanese each character usually has at least two 'readings' for pronunciation onyomi (chinese-origin reading) and kunyomi (Japanese reading).

But often have even more than that, and specifically with peoples names the readings some times feel completely arbitrary.

https://en.wikipedia.org/wiki/Kanji#Readings

Basically, there are multiple ways to get the same 'sound' from different kanji, or get a different 'sound' the same kanji.