Ochame became a war orphan after Earth fell to the Zaar Empire. She saw her parents die during the invasion, held back by civilians from a desperate rescue attempt as they perished inside a burning building. This trauma left her alone and vulnerable in the conquered world's ruins.

She later forged a close bond with Sanae Shiratori, another orphan bearing similar scars. Recognizing their shared loss, Sanae offered Ochame shelter and companionship. Their connection solidified when Kento Tate encountered the pair and offered Ochame stolen candy. Despite Sanae's objections to the stolen goods, Ochame, overcome by hunger and her childlike nature, accepted the treat. This act marked her entry into Kento's band of survivors.

Ochame functions as the group's emotional heart and emblem of innocence, often called "Everyone's Baby Sister." Her presence embodies the human cost of the alien occupation and galvanizes the group's protective instincts. She witnessed Danji Hiiragi's arrival after Sanae brought the injured boy to their hideout, further weaving him into their found family. Her role consistently highlights themes of loss, resilience, and the quest for safety.

Her orphaned past directly shapes her reliance on the group and her portrayal as a vulnerable yet resilient figure. She acts as an emotional anchor for others, particularly Sanae, through their shared history of trauma. The narrative uses her experience to underscore the Zaar Empire's widespread devastation and the harsh struggle for survival faced by Earth's children.