Tax treaty is concluded to avoid double taxation of income internationally and preventing tax evasion.
In the case of tax treaty between Japan and China, real estate income generated in Japan is levied by Japanese government.
So, assumed that Ms Lin who lives in China has real estate and real estate income in Japan, she has to pay real estate income tax in Japan.
And she does not need to pay real estate income tax in China.
In this way, she can avoid double taxation of real estate income.
In order to apply for this treatment, she has to submit Application form for income tax convention to tax agency in Japan by date before of her payment of income tax in Japan.
I am willingly assist you for this procedures.