In 1932, Matsu took part in the confrontation between the Chinese and Japanese forces in Shanghai, where he interrogated Sung-Chi Li. Matsu successfully persuaded Li that Japanese rule could bring back order to China locked in a struggle between Nationalists and Communists, and recruited Li as a double agent.
After war broke out between Japan and China in July 1937, Matsu was stationed in Mukden in Manchukuo. In August, Li attempted to contact Matsu to war him about Hsien-Ko's nuclear reactor hidden inside the mountain of T'ai Shan, and tried to recommend Matsu send an invasion force into Shangdong province. However, Mr Sin severed their means of contact. (PROSE: The Shadow of Weng-Chiang)