Aoi Futaba is a main character from the anime Vividred Operation and is the best friend and classmate of the protagonist, Akane Isshiki, at Oshima North Hill Elementary and Junior High School. She is fourteen years old and has a recognizable appearance characterized by her long blue hair, blue eyes, and fair complexion. In her everyday life, she typically wears a light-blue one-piece sundress with frilly white socks and black shoes, but when she transforms using the Vivid System, she dons a blue Palette Suit that resembles Akane's red outfit.

Aoi comes from a wealthy family, being the daughter of the head of the Futaba Zaibatsu, which means her parents are frequently occupied with their careers and often absent. Due to a poor medical condition that requires ongoing treatment, she relocated from Blue Island to Oshima, which is where she attends school and befriends Akane. Befitting her refined and lady-like image, Aoi is generally soft-spoken and carries herself with grace. Despite her composed exterior, she gets scared more easily than her friends and has a notable distaste for tomatoes, an aversion that ironically played a key role in forming her close bond with Akane.

Aoi serves as the second known user of the Vivid System, following Akane's initial activation. Her role in the story is that of a vital ally and the first person to join Akane in fighting the mysterious alien threats known as Alone. When she transforms, her primary weapon is a massive, two-headed hammer called the Naked Impact, which is incredibly heavy and can be used both as a powerful striking tool and as a shield to deflect incoming projectiles. She possesses immense superhuman strength in this form, demonstrated by her ability to stop a flying fighter jet with her bare hands and carry it to safety. Her most significant ability is the Docking Operation, a process where two Vivid System users combine their consciousnesses into a single, more powerful entity. This is activated by a kiss on the forehead. When Aoi docks with Akane, they become Vivid Blue Operation; in this state, the combined body typically uses Akane's voice and drive while wearing a blue outfit and wielding an upgraded version of Aoi's hammer called the Vivid Impact. Their ultimate attack, the Final Operation, is a devastating hammer strike strong enough to destroy a powered-up Alone in a single blow.

The heart of Aoi's character development lies in her profound friendship with Akane. Their relationship was initially tested during their first attempt at the Docking Operation, which failed because Aoi was subconsciously holding back a secret she thought would jeopardize their friendship: her hatred for tomatoes. Years earlier, when they first met, Akane had given Aoi a tomato as an apology gift, and Aoi, wanting to be friends, pretended to like it. The failure of the docking forces Aoi to confess this secret, but Akane reveals she already knew, as she had seen Aoi's disgusted face when trying to eat tomatoes at school. Akane explains that she valued their friendship not because of a vegetable, but because of the joy they shared, which resolves Aoi's inner conflict and allows their bond to become strong enough to successfully complete the Docking Operation. This event solidifies Aoi's role not just as a teammate, but as the person Akane trusts most, transforming her initial insecurity into unshakable confidence in their partnership.