Yuito's memory of his childhood savior returns. While off duty, Yuito and Nagi run into Naomi and Kasane. Something is afoot in Seiran, but is it related to Karen's agenda? The Seto and Kyoka platoons train, and then scramble to intercept the Others.

Karen's machinations lead to a battle between comrades until a new threat arrives, claiming all around it. Yuito and company lick their wounds as they learn about Karen's motives. Others swarm into Suoh, and Kasane and company awake in a strange place.

Kasane and company wake to a shocking reality and strange encounters. Kasane learns about the void in the sky and a way to stop it. Yuito and Kasane clash after she finds out what is behind Karen's revolt. Kasane heads to Seiran with other OSF members.