No sooner has Nanako Misonoo started attending Seiran, the most prestigious girls’ school in Japan, when she is unexpectedly chosen to join its most exclusive club, the Sorority. Believing that she was given preferential treatment by the Sorority’s leader, the beautiful and intimidating Miya-sama, Nanako’s jealous classmates begin to bully her. Slowly, life at Seiran begins to unravel and Nanako wonders why the Sorority chose her over more eligible candidates. Not only that, what could lie behind Miya-sama’s mysterious smile? With only the letters to her ‘dear brother’ to help her make sense of it all, Nanako must try to find answers to these and many more questions.