This paper applies a performative view, not a communicative view, to thelargest online community in Japan, Channel 2 by analyzing its typical collectiveaction called Yoshinoya Festival, from both aspects of its online communicationsand offline events. Behaviors in online communications are analyzed quantitativelybased on the methodology of CMC studies, and those in offline events areanalyzed qualitatively based on that of cultural anthropology. Then the problematiccharacteristics in Channel 2 are discussed.