In 2021, CiNii—Japan's largest academic information retrieval platform—launched CiNii Research as a unified search engine, gradually integrating and upgrading its modules for articles, books, doctoral dissertations, and research projects. This paper outlines the evolution of CiNii: (1) the infrastructure phase of the NACSIS system (1983–2004), (2) the startup and expansion phase of the CiNii platform (2005–2020), and (3) the integration and upgrade phase of the CiNii Research engine (2021–). It summarizes the key features of CiNii Research, including the expansion of its search scope, optimization of search logic, and advanced English-language search capabilities. Furthermore, by examining the government-led, public-interest platform's commitment to content integration and open access, this paper discusses the implications of these upgrades for academic information services in China's higher education sector.