I have my Russian 200B final exam tomorrow morning, and I'm stuck on something.

Looking through my old tests there is a translation bit with "I don't read Japanese books"

I translated it as (forgive my lack of cyrillic but I'm kind of in a rush) "Ya ne chitayu yaponskih knig"

It was marked correct, but this was 4 months ago and I don't understand for the life of me why Japanese books is in genetive and not accusative.

An explanation would be greatly appreciated.