Ｂｕｔｔｅｒｆｌｙ　Ｋｉｓｓ．ＢＬＡＤＥ

Homura Tsukishima and Sakurako Hirosue are roommates at Principia Academy, a school located on an island created specifically for researching "shiki", which is a form of power created by manipulating numbers.