" I may not be suited for a big bust sized Tail Gear, but it's not worth Soji losing their life over something like that . . . . gimme that blue bracelet !!! "
- Aika Tsube (津辺 愛香? Tsube Aika) / Tail Blue (テイルブルー? Teiru Burū)
- Both Aika and TailBlue are voiced by: Yūka Aisaka
- (Japanese); Sarah Wiedenheft (English)
Aika is about the same height as Soji, medium body with a slightly thinner body build, due to her being very athletic. She has a slightly angular face, with a slightly pointed chin. Aika has very long dark blue hair, that she has always worn in the twin tail hairstyle. She has deep set anime girl 'big eyes', with a reddish-maroon color. Her skin tone is beige with a faint pinkish color, and with a very even texture overall. Unfortunately, although she has a very attractive appearance, Aika has over time developed a complex dysphoria with the look and shape of her body, especially with her flat, underdeveloped chest. Refusing to wear a padded bra, she opts for wearing a training bra, or a sports bra. She is quite sensitive about her small bust size and shape, and is quick to take offense at any mention or hint of it. However, her school uniform's mini-skirt shows off her long, thin legs.
Most often seen at school, Akia wears the female school uniform. This consisting of a white blouse with a fluffy powder blue bow tie, an attached black pleated mini-skirt, a beige with black trim ladies business jacket, and black thigh-high stockings with black oxford shoes. For casual wear, Aika typically wears a T-shirt with denim booty shorts, and thigh-high stockings, or bare legs, and athletic shoes. Sometimes she will wear a pretty dress, which will make her look like a little girl. Despite Aika's feminine dress and grooming, If it wasn't for her long, blue twin tails, many humans and Elemelians would often mistake her for an adolescent, abet feminine, teenage boy. This she takes in stride, not worrying about what others think of her or her appearance.