Aika Tsube is one of the main heroines of Ore, Twintail ni Narimasu series. Aika is Sōji Mitsuka's childhood friend, she lives the next door to him, and their room are heading the opposite sides, so they are able to talk every time. She gained the Tail Gear and transform into Tail Blue (テイルブルー?) the time Sōji gained his power.
Aika has dark blue hair and red eyes. Her long hair is styled into twintails with white ribbon, which can reach her waist.
Aika is a normal schedule old girl with her serious attitude.
She is also pretty abrasive when she feels that her position with Soji is threatened, when Thouars is doing something 'stupid' (sometimes both at the same time) or provoking her for her flat-chest in both civilian and tail forms, resorting to violence and threats against the perpetrator.
- Her birthday is August 8.
- It is hinted in Episode 1 that her favorite food is curry.