This study analyzes diaries of key Taiwanese political activists during mid-Japanese colonial rule, employing the Taiwan Web-SNA & GIS platform to examine social networks and trajectories after the Taiwanese Cultural Association split. The analysis clarifies complex diary relationships and reveals hidden connections, providing insights to supplement or revise existing historical interpretations. It identifies Tsai Pei-huo and Lien Wen-ching as critical intermediaries between left-right factions early on, while Luo Wan-chu later emerges unexpectedly central. Wen Cheng-lung notably became Lin Hsien-tang's essential informal mediator around the Taiwanese People's Party's collapse. The social network analysis also proposes alternative reasons for the continued operation of the Taiwan Local Autonomy Alliance post-1931 political crackdown.