Aoi Housen

At 16 years of age and a childhood friend to Kouji, Aoi has known the Aiba brothers longer than anyone outside the Aiba family and acts alternately as an older sister and a mother figure to both boys, often going out of her way to check up on them. A flight attendant trainee aboard the Liebe Delta, Aoi often sticks her nose into Kouji's business. Outside of her dealings with the Aibas, Aoi is fast friends with her fellow flight attendant Kozue Izumi. She is also friends with classmate Reiko Ichikawa, though this relationship is not as close as the one with Kozue.