The sudden outbreak of COVID-19 pandemic and the resumption of production and work expose the shortcomings of Japanese society，but also provide the time and conditions for the Japanese government to advance the digital economy development. The development of digital economy in Japan is mainly based on the Social 5.0 strategy，artificial intelligence，and the large-scale international cooperation. The Society 5.0 strategy is a new concept proposed by Japan after Germany’s Industry 4.0 and America’s Industrial Internet，aiming to crack the existing problems in Japanese society by penetrating into social life through digital technology integration. The artificial intelligence industry is one of the industries to which Japan attaches great importance and is considered to be the core of the fourth industrial revolution. Therefore，a series of policies have been introduced to promote Japan’s core competitiveness in artificial intelligence. International cooperation is another focus point of Japan’s development of its digital economy，aiming to provide convenience for Japanese ICT companies’ access to overseas markets. From the perspective of cities，Tokyo and Tsukuba are typical representatives of digital economy development，but the paths of digital economy development in these two cities are different. Tokyo focuses on the integration of digital technology and social life in all aspects，which is a concrete implementation of “Society 5.0”，while Tsukuba focuses on the development of semiconductor industry and promotes it with full force.