Aiko is the third child after Nezuko. Making sure everyone is fine and waiting for her elder brother to come back. Until on the early morning see witnessed an assassin called Muzan who killed her whole family and turning her and her elder sister demons. Unlikely Aiko hasn't completely turned into one and got rescued by an old lady called Tashiro-Shoto who was an ice breathing former who taught Aiko how to use ice breathing and in the end she became a demon slayer and on her way to slay demons and to fine her older brother Tanjiro. She has a strong sense and can sense in long distances