The first friend Akari makes on Aqua, Aika is 16 when they meet. Aika is a Pair and then Single at Himeya Company. She is the only daughter and heir of Himeya Company's owners, but does not enjoy the distinction as she feels the company's employees fawned on her too much. Aika speaks bluntly and often responds to Akari's idealistic comments with "Embarrassing remarks are not allowed!".