Riri enters Yurigaoka Girls' Academy to become a Lily and protect people from the Huge, but finds her fellow Lilies more competitive and combative than she'd imagined. When a Huge specimen escapes, can Riri survive her first battle with no training?

Riri is overjoyed that Yuyu is now her Schutzengel, but can she hold up under Yuyu's harsh training? Then, when a powerful Huge attacks, Riri gets a glimpse of Yuyu's secret.

Riri finds a mysterious girl in the remains of a dead Huge. The amnesiac girl quickly grows attached to Riri, who devotes herself to taking care of her. But just who is this girl, and how will Riri's legion deal with her absence?

The most powerful Huge yet is attacking Yurigaoka, and Riri is the only one left who can fight! Can Yuyu overcome her past in time to join her? And what can the other Lilies do against an enemy that disables their weapons?