Ichika's 24 year-old older sister, and homeroom teacher of his class at the Academy. She was the Japanese pilot for the first-generation IS machines and was said to be the strongest IS pilot at one point before retiring. During her retirement, she looked after her brother and raised him by herself after their parents abandoned them at a young age. Although she usually treats him coldly, Chifuyu deeply cares for Ichika, as she sees him as her only family. Chifuyu was also the one who enrolled Ichika to the IS Academy to keep him safe from other countries.
Chifuyu once wielded Yukihira, a powerful IS energy blade now in Ichika's possession. Chifuyu was a close friend of Tabane Shinonono, which explains how their younger siblings became childhood friends. Tabane also implies (heavily) that Chifuyu piloted the "White Knight" (白騎士 Shirokishi)–the first ever developed IS that protected Japan from a missile attack 10 years prior to the series.