Keiko Onuki
Keiko Onuki is Shougo Kawada's girlfriend from his previous school in Kobe; Keiko was in Shougo's class when the two were in a Battle Royale. In the novel, Shougo loses track of Keiko; Shougo believes that Keiko felt afraid of him. Shougo later discovered Keiko dead. In the manga, Shougo and Keiko meet. When Keiko seemingly points her gun towards Shougo, Shougo kills her; he later discovered that Keiko had aimed at a person behind him. (Source: Wikipedia)