A trip to the water park turns chaotic. Misa seeks to find the source of the virus that brought the Daemons. The ladies prevent a possible disaster.

The past and present stories are told together. In the present, Koyomi travels back in time. In the past, the reason for Guibarthez's pursuit of the Kerykeion is revealed. Misa resolves to fight Guibarthez.

Yumiko and Guibarthez finally meet for battle. Yumiko and Misa show up to help. Recalling past advice from her parents gives Yumiko the tools to defeat Guibarthez.