The Tokiwadai team competes in the Balloon Hunter event, but due to a case of mistaken identity, one of the Sisters substitutes for Mikoto. Yoshio Baba feeds the other school's team with data on the Tokiwadai competitors, with surprising results.

With Kongo out of danger, Awatsuki finishes the task of having her psychometrist friend probe the kitten's memories. What Saten hears gives her pause, and she turns to Kuroko for advice. Kozaku confronts Mikoto, asking her about the Sisters.

Kamijo and Sogiita find that at best, they can only slow down Mikoto's transformation. Kuroko continues to search for Kozaku while dodging her puppet. Gensei pursues Shokuho for the access code that will let him unlock Exterior's potential.

A young Kozaku grins and bears her way through her youth in an Academy City research institution, where she befriends Dolly, one of the other girls there. But when Kozaku learns the grim truth about Dolly, it sets her on a life-altering course.