Chihiro Kitagawa, born Chihiro Aikawa, is the daughter of Akihiro and Chiaki Aikawa. She stands as the older sister to Kazuhiko Aikawa and the younger sister of Akihiko Aikawa. Following her marriage to Tōru Kitagawa, she became the mother of their son, Kakeru Kitagawa. Her familial dedication shines through her active support for younger brother Kazuhiko's basketball pursuits. Recognizing that their family environment eroded his passion for the sport, she orchestrated his transfer to Mizuho High. Though the manga omits specifics, the anime reveals her leveraging connections with former university teammate Kyōko Himuro to secure Kazuhiko's enrollment.

The Mizuho apartment Kazuhiko occupies post-transfer originally served as her own residence, underscoring her hands-on role in his transition. She remains invested in his athletic journey, attending pivotal events like the Rookie Tournament's prefectural final alongside her son Kakeru. During the Inter-High final, she joined her mother Chiaki at their Niigata family home to watch the televised broadcast live.