Mirai Yashima, later known by her married name Mirai Noa, is a central character in the Universal Century timeline. She is introduced as a civilian colonist living on Side 7, the daughter of the influential Shu Yashima, a former high-ranking official in the Earth Federation government and the head of the Yashima Heavy Industries company. Following the death of her father, she relocated to Side 7, only to be caught in a surprise attack by the Principality of Zeon that forced her to evacuate aboard the assault carrier White Base.

Possessing a license for a cruiser-class space glider, Mirai volunteered to become the ship's helmsman when the regular crew was incapacitated, a decision that marked the beginning of her military career alongside other young civilians like Amuro Ray, Fraw Bow, and Hayato Kobayashi. Her personality is characterized by a gentle, well-mannered, and home-loving nature, which stems from her privileged upbringing. This demeanor quickly establishes her as a surrogate mother figure to the youthful and often emotionally volatile crew of the White Base, a role for which she is deeply respected. Despite her composed exterior, Mirai struggles with emotional insecurity and a distrust of others, traits aggravated by the early loss of her father and the immense pressures of the war.

Within the story, Mirai serves as both the principal helmsman and the trusted deputy to the ship’s captain, Bright Noa. Her keen observational skills and sound judgment make her an invaluable advisor, and she often acts as a counterbalance to Bright's more aggressive tendencies, providing a steadying hand during crises. While she is capable of assuming command, as she did briefly when Bright collapsed from overwork, her skills are best suited for ship handling and support rather than large-scale tactical command. Her relationships are a significant part of her character development. She is reunited with her former fiancé, Cameron Bloom, on the neutral colony of Side 6, but finds his cowardly and self-serving desire to flee from the conflict repulsive, leading to the end of their engagement. During the war, she also develops a brief but intense attraction to the brash pilot Sleggar Law, who ultimately perishes in battle, leaving her to mourn the lost possibility of a future with him. After the war, she marries Bright Noa, and they have two children, a son named Hathaway and a daughter named Cheimin.

Throughout the Gryps Conflict and the Second Neo Zeon War, Mirai remains a figure of resilience. She is forced to navigate the dangers of being a Federation officer’s family, at one point moving her children out of a military residence that served as an informal hostage situation to ensure her husband’s loyalty. In Char's Counterattack, she makes the poignant sacrifice of giving up her own seat on an evacuation shuttle to send her son, Hathaway, to safety in space. Her notable abilities extend beyond her technical proficiency as a helmsman. Mirai possesses a powerful intuition and sharp insight that borders on Newtype potential. She is frequently among the first to sense danger or detect the supernatural phenomena associated with powerful Newtypes, such as Amuro Ray and Lalah Sune, demonstrating a sensitivity that manifests earlier than even Amuro’s in some respects.