Shimai is Isamu's half-sister, although he doesn't know it yet. She is a in Hama Town with her aunt. She is also a Shade whitch are a group of people to attain both Shinigami and Hollow powers at the same time. She is the Leader of the Paladins, the Shade that have forced their Hollow powers into their Zanpakuto and turned them into Arrancar like Zanpakuto while the Shade themselves gain Shinigami-like powers (e.g They can use Kido, Shunpo, Etc).