Sister of Satomi Renbokouji, who is pretty much a paranoid hikikomori that confines herself in some inconspicuous corner in the school's lower basement often being in front of her computer. She is depended on her brother (later, on Shoko) to bring her food and other personal necessities, she spends most of her time checking out various social medias, and hacking into the school's security cameras and students' cell phones, it is suggested that even as a recluse she is aware of the JIOR army's top secret project involving the Valvraves, but was too afraid to tell anybody.

(Source: anime44 forum)