The series of the Japan Conference on Discrete and Computational Geometry, Graphs, and Games (JCDCG3) has been held annually since 1997. In 2012, the series of the conference was held at Srinakarinwirot University in Bangkok as “Thailand-Japan Joint Conference on Computational Geometry and Graphs (TJJCCGG 2012)”. Due to the COVID-19 pandemic situation, the event planned in Chiang Mai in 2020 was postponed. It is time to continue the conference by 100% online format this year, organized by Chiang Mai University, Thailand.

       The topic of the conference includes but not limited to: Discrete Geometry, Computational Geometry, Graph Theory, Graph Algorithms, Complexity, and Winning Strategies of Games and Puzzles

	Kokichi Sugihara Meiji University Distinguished Professor Emeritus Tokyo, Japan		János Pach Rényi Institute of Mathematics Budapest, Hungary
	Erik Demaine Massachusetts Institute of Technology USA		Stefan Langerman Algorithms Research Group, Université Libre de Bruxelles, Belgium
	Jittat Fakcharoenphol Theory Research Group, CPE Kasetsart University, Thailand		Daniel Horsley Monash University Australia