Ayako, who could not have children with her husband, Ke'ai her nephew Ataru as if he were her own son. Ataru also admired and liked Ayako's kindness. As time passed, Ataru started working near Ayako's house, and while his uncle was away on a business trip, he decided to commute to work from Ayako's house, where she was lonely. One day, Ayako suggested that they set off fireworks.