Infected Digimon, wild and powerful creatures, are invading the real world. Maki Himekawa and Daigo Nishijima, who work for the mysterious Incorporated Administrative Agency, are investigating these disruptive occurrences. Meanwhile, the Chosen Children are busy getting ready for Tsukishima General High School's summer festival. Mimi Tachikawa has recently returned to Japan after living in America for years, and is struggling to fit in with her peers and fellow Chosen Children. Jou Kido, on the other hand, is intentionally avoiding anything to do with Digimon by focusing on his education, causing his partner Gomamon to leave. Mimi and Jou's choices drive a wedge in the group as the threat of infected Digimon looms. Will they be able to resolve their personal issues in time to help their friends confront this new danger?