The sole female member of Gridman Alliance and Yūta's classmate, who found the amnesiac boy in front of her house. Out of her teammates, she desires a normal life but wishes Yūta to keep fighting as Gridman to save her friends. Once discovering Akane's double life as the creator of the monsters, Rikka becomes committed to reason with her friend despite the former's insistence that their friendship was not genuine. Before Akane leaves for her world, Rikka gives her a purse case as a departure gift.