Japan wasn't always good. But they analysed what worked and what didnt. They spent decades building up local talent. Today is a product of that hard work.
China on the other hand never figured it out. They tried hiring foreigners who were rejects elsewhere and we know that doesn't work but costs a lot. But we can see the vast majority of Chinese players flat out suck. I believe the selection process is completely wrong and needs to replaced entirely. Fun fact, Wu Lei who is the star striker and the only good player imo wouldn't have even gotten in the team coz he wasn't tall enough and had to get a special recommendation. He also played in Spain for a while while most Chinese players never left China.
Team sport infrastructure is a different beast from single sport. It has to be good or you will fail. You can't rely on a single genius to mask it like how even though MMA ain't big in China, Zhang Weili is currently a UFC champ.
What is China doing differently with their Women's team? Women's team seems to be good. They are ranked number 17, even higher than South Korea.