In Chinese tho with extremely rare exceptions all the characters have only one reading.

Japanese has onyomi and kunyomi. The onyomi also come from different periods in Chinese so there's multiple onyomi for most Kanji.

Then you get two Kanji words that come in all varieties. Most are onyomi + onyomi, but you get some that are onyomi + kunyomi or kunyomi + kunyomi or kunyomi + onyomi.

There's also not really any solid rules to it, and when there are, there are plenty of exceptions.

It's a real nightmare of a system. A fun one though.

And then you have nanori, the non-standard readings used for people and places names that are impossible to read without furigana or already knowing the name. One that really surprised me was a village called 愛子 (a common female name read as "Aiko") near Sendai but in this case read as "Ayashi".