The character known as "Onee" or "Sis" belongs to Eden, a group formed by Saki Morimi's friends. Eden develops and operates a smartphone application utilizing image recognition and social networking to identify objects and people. This group investigates the Seleção conspiracy after gaining access to the Seleção database. Onee works alongside Eden members Kazuomi Hirasawa, Yutaka Itazu, Satoshi Ōsugi, Haruo Kasuga, and Mikuru Katsuhara. During a depicted missile crisis, Eden assists Takizawa in formulating a response, applying their collective technical skills and application resources.

In the subsequent film *The King of Eden*, Eden evolves into a successful business. The group continues supporting investigations into the Seleção game, using their database access to track developments and aid Saki's search for Takizawa. They face cyberattacks from Seleção Daiju Mononobe, forcing temporary shutdowns of their operations.

During *Paradise Lost*, Eden members retreat to their university campus but remain involved countering Mononobe's schemes. They assist Takizawa in locating critical infrastructure for the game, including the trucks housing the Juiz supercomputers. Members like Katsuhara and Sis directly participate in hijacking one of Mononobe's Juiz trucks. Information regarding Onee's personal background, specific role within Eden beyond general membership, individual character development, or unique contributions across the series or films remains limited to the collective actions of the Eden group.