First of all, carry out the procedure to marry him, and then go to the nearest Immigration office to apply for special permission to stay in Japan. After that, your application will be examined, which takes some time. When they judge your marriage is genuine and not against the law, there will be a possibility for you to obtain the visa. I'll explain separately about marriage and immigration procedures.

1) Ask your parents in China to send you official documents such as your birth certificate, proof you are not currently married, nationality and family tree. Also, ask your partner for his family registration. Take them to your local city office and follow the necessary steps to get married. At the same time, we recommend that you take the appropriate steps to renew your foreign registration card. After completing the procedures for your new family registration and foreign registration card, you will need to take another step.

2) After getting the appropriate documents ready including the application, his family registration and resident's card, any document that certifies your incomes and lives such as job certification, a tax deduction certificate, a certificate of tax payment, a house rental contract, photos of you both, etc., as well as your alien registration card, the two of you will need to go to the nearest Immigration office. Although it takes a lot of time, there is possibility that you can obtain a Japanese spouse visa unless your marriage is not genuine or you have done something illegal.