The Research Seminar on May 4, 2020 was held online with Dr. Han Zhang from the Hong Kong University of Science and Technology. Dr. Zhang presented his method based on deep learning to detect offline collective behavior in China, which uses text and image data from the Chinese social media, Weibo. The analysis utilizing that method showed quantitative and qualitative changes in offline collective behavior since 2012. About 60 participants participated in the seminar, and a lively discussion took place.