What kind of visa do China and Japanese need to get married and live in China?

China does not recognize dual nationality, so she can leave Japanese nationality and join China nationality. You can apply for a green card in China. Also, if you want to live with her in Japan, you must become a Japanese citizen. Japan recognizes dual nationality, but China does not, so joining Japanese nationality will automatically leave China nationality (see China Nationality Law for details). When you return to China, you will be sent back to Japan as an illegal immigrant. Similarly, if she wants to get a green card in China, she must give up her Japanese citizenship.

So it may be easier to apply for a visa. But many things will be inconvenient in the future, such as social welfare and insurance. When the visa expires, you can apply for a visa extension once a year, because it seems that you can apply for an extension of one year at most. You can apply for permanent residence after living in China for five years, but this is not naturalization but a permanent visa, and you do not enjoy any rights and welfare obligations of China citizens.