This 99% number does not mean what people think it means. The Japanese prosecution system is a pipeline that strongly filters out unlikely-to-be-convicted cases from the very beginning. Long before you are convicted, you might not even be arrested, or your case gets dismissed earlier in the pipeline. Here is a video, with references, from a relatively trustworthy source: https://www.youtube.com/watch?v=OINAk2xl8Bc
Sure, absolutely the Japanese justice system has some serious problems, just as the American one does. But let's not pretend that they're remotely comparable to the CCP.
Unfortunately this doesn't mean what people might think it means. "Unlikely-to-be-convicted" doesn't mean much when the police have so many tools available to force confessions, whether the person is guilty or not.