Daihaseisai or Daihasei Festival (大覇星祭 (だいはせいさい) Daihaseisai ?, lit. "Grand Champion Star Festival") is an annual city-wide interschool sporting competition that takes place September 19 through September 25 in Academy City. It is a major milestone in the Toaru Majutsu no index story, with currently two story arcs occuring during the events of the festival.