Chifuyu is Ichika’s older sister. She is 24 years old and is in charge of Ichika’s class at the IS 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. She 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 that is now under Ichika’s possession. Chifuyu was a close friend of Tabane Shinonono, the creator of the IS, which explains how their younger siblings became childhood friends.