Oicho begins as a member of Sachio's street children group in the first season, speaking sparingly and primarily appearing in the background. Her physical traits include olive-colored light hair and ochre eyes, reflecting her Japanese heritage. During the second season, Nomad, she experiences significant growth by apprenticing as an engineer under Abuhachi at his repair shop. This role shifts her from background presence to active contributor through hands-on technical work and more substantial narrative interactions.