When the world faces a crisis with the sudden appearance of monstrous creatures called the 'Huge,' teenage girls known as 'Lilies' step up to protect humanity using their inner energy, 'Magie,' to operate powerful weapons like 'Counter Huge ARMS' or 'CHARMS.' Inspired by a Lily's heroism during a Huge attack, Riri Hitotsuyanagi joins Yurigaoka Academy, a renowned school for Lilies. To her surprise, she discovers her savior, Yuyu Shirai, amongst her classmates, only to find out that Yuyu is not the cheerful companion she envisioned but a solitary and standoffish fighter. Despite this, Riri is determined to bridge the gap with Yuyu and strives to build a connection. With Yuyu and other Lilies as her allies, Riri embarks on a journey towards fulfilling her newfound aspiration.