Ayumi Hayami is the daughter of Captain Youhei Hayami, commander of the submarine 707. Primarily featured in family scenes contrasting with her father's naval duties, she expresses sadness over his frequent absences, highlighting the personal sacrifices of military families.

During an attack on naval vessels depicted in the visual novel spin-off "Ayumarine 707R Mission:02," Ayumi reunites with her father but becomes confined aboard an enemy submarine. Held captive amid its sexually frustrated male crew, this situation creates vulnerability and tension, raising personal stakes for Captain Hayami beyond his military mission.

Domestic scenes with her mother humanize Captain Hayami, illustrating his family relationships and the cost of service. Parallel scenes featuring Admiral Red's wife and children create a narrative contrast between the opposing commanders as fathers. Ayumi's presence contributes to themes of familial bonds amid conflict.

Her voiced performance of the ending theme "Ichiban Boshi" for the first episode connects her character to motifs of separation, expressing the longing of family members left behind during military deployments.

Her narrative function centers on her relationship to Captain Hayami and symbolizing the domestic sphere affected by warfare.