Aki was born in San Francisco Barrier City in 2038. She was orphaned at an early age when her parents fell victim to Phantoms and was raised by an aunt in New York Barrier City. Following the footsteps of her father, a respected scientist, Aki dedicated her life to understanding biotechnology. Outspoken in her opinions and ideas, Aki became an expert in her field at an early age. She would travel between the barrier cities, conducting experiments and lectures with other scientists. Under the supervision of renowned scientific theorist Dr. Sid, Aki began research on his wave-theory.

Aki trained at the Houston Military Academy (HMA), the institution responsible for military training in the United States Military Force and United States Air Force. Focusing on aerospace education, she received environmental and wasteland reconnaissance training, and entered a relationship with fellow military student Gray Edwards. Upon her graduation Aki returned to New York Barrier City to complete her doctorate, while Gray was assigned to the Deep Eyes military unit. They continued their long-distance relationship between Gray's missions and Aki's commuting to other barrier cities.

Aki had became a dedicated scientist and advocate to Dr. Sid's theory to try and eliminate the Phantoms without using excessive force. Due to an accident during an experiment Aki was infected with Phantom particles. Secretly moving to the Zeus Cannon, Dr. Sid isolated the Phantom particles using wave-theory as a temporary solution. Weary of the magnitude of her condition and determined conceal it, Aki cut off her relationship with Gray without giving an explanation, turning her attention to completing the wave-theory. She and Dr. Sid set out to find the eight remaining spirits to defeat her infection and find a peaceful solution to the Phantom threat.

In the following months Aki tracked down and retrieved spirits; a fish, a deer found in a wildlife preserve outside Moscow, a sparrow, and the spirit of a dying girl. The experience of the last retrieval affected her deeply and brought her own terminal infection and the status of the world in general into focus. She began having recurring dreams of an alien landscape. Deducing that the dreams are brought on by her infection, she began recording them in hopes of finding insight into the species.

While retrieving the sixth wave spirit—a plant in the New York wasteland—Aki is assisted by a Deep Eye squad of four who specialize in wasteland recon. Rescued by the squad, she and her ship are brought to New York Barrier City, and she discovers one of her rescuers is an irate Gray Edwards, now a captain and squad leader of his own unit. Agitated about going through the city's contamination detector due to her infection, she bypasses it by saving Gray from an infection of his own that he had sustained during his squad rescuing her. This, and the timely arrival of Doctor Sid, allow her to enter the city with her affliction undetected. Later, to prevent any drastic action by the United States Military Force and buy time for Doctor Sid's wave theory to be implemented, Aki reveals the affliction to the council as a testament to the credibility of Sid's claims.

Her secret revealed, Gray seeks her out, finding her embarking on a scan of the city for the seventh spirit. The two rekindle their relationship due to the mischievous actions of Gray's Deep Eye squad. A suspicious General Hein temporarily assigns Gray's Deep Eye squad to accompany Aki on her remaining voyages and orders him to report any suspicious behavior. To ensure Gray's compliance he orders Major Elliot to insert some of his own men into the squad.

Sensing that her infection is winning, Aki's search for the seventh spirit leads her to the Tucson wasteland and the remnants of the Phantom Cleansing Mission. The Deep Eye squad accompanies her through the wasteland, deducing that the spirit is the living energy inside the Ovo-pack of a dead soldier. After the spirit's retrieval, Aki is overcome by the infection within her, which begins drawing other Phantoms towards her. She falls into a dream-filled coma, but awakens momentarily during the hectic escape only to fall victim of friendly fire by one of Hein's men, falling unconscious again.

Returning to the New York Barrier city, Dr. Sid reinforces the infection's containment by introducing the waves from all the currently collected spirits. Gray acts as her spiritual support, entering her dreams to ensure she wouldn't be overtaken by the Phantoms before the containment is complete. Aki's chest plate is repaired and she awakens only to be thrown into a detention cell along with Dr. Sid and the squad after General Hein finds cause to suspect that she is being controlled by the Phantoms.

The incarceration is short-lived as, due to General Hein's attempts to stage a Phantom invasion, the barrier city's power grid goes off-line. The group escapes from the prison ward to discover the barrier city overridden by Phantoms. They make their way to the hangars where the Black Boa is being detained, but only three (Aki, Sid, and Gray) escape to safety aboard the ship, as the others are killed.

Resting in space, Aki and Gray comfort each other over the deaths of their friends, leading to them becoming intimate in their grief. Dr Sid begins the search for the eighth spirit and enlarges the search field to include the Phantom crater in the Caspian Mountains. Locating it as a Phantom, Aki and Dr. Sid devise a plan to obtain the eighth spirit by lowering Aki and Gray into the crater and fusing the spirit with the other seven spirits on location. When an energy beam from the Zeus Cannon hits the meteor, the eighth spirit is seemingly destroyed.

As the cannon continues its attack the Phantom Gaia appears from the meteor that originally brought the Phantoms to Earth. It begins to grow, dragging down the pod Aki and Gray are in. Despite pleading for Hein to stop, saying the attack is doing more harm than good, Aki's cries fall on deaf ear. General Hein continues to fire the cannon despite warnings of a system overload.

The pod damaged, Aki and Gray had landed between the Earth Gaia and the emerging alien Gaia. Being this close to Gaia allows them the best possible location to find another eighth spirit. After falling comatose, Aki discovers the final spirit is within her. Linking to the chest plate that contains her infection, and using the Ovo-pack of Gray's gun, she reroutes power into the pod's shields and emits the combined wave of all eight spirits.

The combined wave destroys the Phantoms, but a final beam from the overloading Zeus Cannon penetrates and weakens Gaia, allowing the Phantom Gaia to grow and begin infecting the planet's soul. With the pod rendered inoperable due to the blast there is no way to transmit the wave. Gray, mortally wounded, sacrifices himself to transmit the completed wave inside Aki directly into the Phantom Gaia, and the Phantoms and their Gaia are destroyed. As Dr Sid, on board the Black Boa, winches her from the crater, Aki cradles Gray's body in her arms and watches the world's life return, signaled by a flying bird overhead.

