Since you have no problem with Japanese, you can take the postgraduate exam in any major you like, which will greatly increase your choice. In addition, in addition to exchange students, you can also consider national scholarships, but you must contact the school yourself, and the procedure is more troublesome.

The following universities are Hokkaido University's study abroad agreement universities. Generally speaking, these universities have the opportunity to exchange students and cultivate something together:

Zhejiang University

Peking University

Fudan University

Jilin University

Nankai University

Nanjing University

Xi’an Jiaotong University

Tsinghua University

The following agreement universities of Kyushu University:

Sun Yat-sen University

South China University of Technology

South China Agricultural University (SCAU)

Peking University

Jilin University

xinjiang normal university

Beijing Normal University

Tsinghua University

China university of science and technology?

The University of Hong Kong

The Chinese University of Hong Kong

Sichuan University

Zhejiang University

Shanghai Jiao Tong University

Fudan University

Renmin University of China

Nanjing University

Beijing University of Aeronautics and Astronautics?

Xi’an Jiaotong University

Northeast Teachers University

Tongyou University

Wuhan University

Nankai University

Huazhong University of Science and Technology

China Agricultural University

In addition, if you don't have a favorite major, ask the old classmates in these schools. As far as I know, exchange students often have professional restrictions, so the chances of choosing the major with the most exchange students are greater.