Five years before the story begins, otherworldly invaders known as Incubi emerged and began using human beings as breeding material, pushing humanity to the brink of extinction. In response, a handful of girls awakened to a supernatural power called Magic and became Witches — magical girls who now fight the Incubi across the world. Among them is high school student Renka Azuma, who transforms into Silver Lotus, a Witch who commands a swarm of insect familiars called the Insect Familia. Unlike most Witches, Silver Lotus operates entirely in the shadows, systematically hunting and exterminating Incubi without ever stepping into the public spotlight.

The top-ranked Witches, known as the Numbers, take notice of Silver Lotus’s growing record and repeatedly invite her to tea gatherings in an attempt to gather information about her, but she rebuffs every invitation. Meanwhile, the Incubi, having suffered repeated raids from her insect familiars sent deep into their territory, come to view the mysterious Silver Lotus as a Calamity Witch and begin to target her directly.

A turning point arrives when Silver Lotus rescues a novice Witch named Azure Nova from an Incubi attack. Azure Nova immediately declares herself a fan and becomes a persistent presence in Silver Lotus’s otherwise solitary life. Through this unexpected connection, Silver Lotus’s daily routine begins to shift, drawing her into broader conflicts with other Witches and the Incubi alike.

As the Incubi intensify their scheming to bring back intelligence on the Calamity Witch, Silver Lotus mobilizes her familiars en masse beneath the old capital, setting the stage for a desperate extermination battle where both sides are fighting for survival. The story follows her unorthodox methods — using insects to devour and destroy the Incubi — and the dark, morally ambiguous path of a magical girl who is as much a predator as the monsters she hunts.