Homura Tsukishima and Sakurako Hirosue are roommates at Principia Academy, a school built on an isolated island that exists solely for the study of shiki, a unique form of power generated through the manipulation of numbers. Students at the academy are trained to develop and control these abilities, which are central to life on campus and likely tied to the school's true purpose. The story follows the daily lives and deepening relationship between Homura and Sakurako as they navigate the challenges of their studies, the mysteries behind shiki research, and the growing romantic tension between them. Their bond, initially one of convenience as roommates, gradually becomes more intimate and complicated against the backdrop of a school that blends academic routine with hidden conflicts and physical confrontations. The narrative balances lighter comedic and romantic moments with more intense fighting sequences, exploring how the two young women rely on each other both in and out of battle. The complete story unfolds over a single volume, with seven chapters that build toward a resolution of both the personal and the larger institutional conflicts surrounding the nature of shiki and the academy itself.