His death, widely seen as a government effort to quell student activism, sparked widespread anti-government protests across China in November and December 1947.

In response to diminishing student backing, Hong travelled to Hangzhou, where he established a local branch of the New Democratic Youth Federation (YF).

In October 1944, Yu Zisan enrolled in NCKU's College of Agriculture, relocated to Yongxing, Guizhou during the Sino-Japanese War.

In 1946, Yu joined the covert student society 'New Tide' and was elected SAA chairman, leading protests against the Peiping rape case and against hunger, civil war and political suppression.

[1] On 25 October 1948, following his attendance at a NCKU alumnus' wedding in Hangzhou's city centre, Yu Zisan visited Datong Inn.

There, he and three other NCKU students – Chen Jianxin, Huang Shimin, and Li Bojin – were apprehended by agents from the Central Bureau of Investigation and Statistics (CBIS), the KMT secret police.

[7] During the search of the students' possessions, Chen's letters were discovered, outlining plans to establish 'New Tide', a new organisation involving Yu, based on profits from a peace orchard in Fenghua.

Additionally, books deemed Communist, including Shen Zhiyuan's 'The Academic History of Modern Economics' and Karl Marx's 'The Poverty of Philosophy' and 'Wage Labour and Capital', were found in Chen's belongings.

Despite Chu's insistence on judicial handling, the Hangzhou police head claimed the evidence was substantial and a court hearing would occur within a day or two.

[1] On 26 October, upon learning Yu's arrest, the NCKU branch of CCP, headed by Xu Liangying, urgently convened at the School of Engineering.

Due to the recent influx of new members in the communist organisation, Xu endeavoured to reassure them and sought to leverage public opinions, including the SAA and the wider university community, in efforts to secure Yu's release.

[6] Following Yu Zisan's death, Chu Coching, the president of NCKU, accompanied by university staff doctor Li Tianzhu, rushed to the Garrison Headquarters.

Shen Honglie, the governor of Zhejiang, and the Ministry of Education, for fear of the nationwide impact, attempted to negotiate with Chu to retract the decision.

After a meeting with Zhu Jiahua on 5 November for further deliberation, Chiang directed that a trial be conducted as promptly as possible and ordered a comprehensive investigation into the circumstances surrounding Yu's death.

Governor Shen Honglie was incensed by the SAA's efforts to bury Yu in the university cemetery and their plans for a parade in downtown Hangzhou.

This decision led to clashes with local porters and workers, who had been adversely affected by the prolonged curfew near the university campuses and feared that escalating student activism might exacerbate their plight.

Following negotiations with Chu, which stipulated no parade or rally and limited attendees transported by three trucks, Yu's body was interred in the university cemetery at Phoenix Mountain, under restrained circumstances.

Later, in July 1949, when CCP planned to invite Chu to resume his role as president at NCKU, he faced opposition from the students blocking his return.