For most of her first 17 years of life, Chitose has been hospitalized for an incurable illness. Having no friends, she would stay in her room at all times watching through the window healthier people play outside and counting the leaves on a nearby tree. As an attempt to cheer her up, the Angels paid her a visit, during which she collapsed and asked to be one of the Angels before she dies. Her request was granted.
Once among their ranks, however, Chitose’s tactlessness failed her attempts to make friends and led to her being shunned by most of the Angels. Feeling rejected, she vowed to destroy the Angels and joined the rival Galaxy Twin-Stars as part of her vengeful plan. Thus begun a one-sided antagonism between Chitose and the Angels, as Milfeulle still considers her to be a very good friend and the others having either forgotten who she was or became indifferent. She would later be reassigned back to the Angels and would try to be their friend again as well as destroy them.
Although generally a nice and sweet girl, Chitose vacillates between wanting to make friends with the Angels and wanting to kill them. Fortunately, her desire for revenge is hampered by ineptitude and what seems to be bad luck, often inflicting serious harm upon herself rather than others. Unfortunately, her ability to make friends is also mired by ineptitude and bad luck, also resulting in self-injury as well as a renewed determination to kill. In the end, she rejoins the Angels.
After her service in both the Galaxy Angels and Galaxy Twin-Stars, Chitose stayed in the military as an accountant at age 21. Buried in paperwork, her life has (relatively) never been more miserable.
However, in volume 2, it is revealed that Chitose has unwittingly been mind-controlled by Noa all along. Noa tries to make Chitose kidnap Prince Shiva, but Chitose regains enough of her own mind to kidnap Takuto instead.
Highly experienced in archery, Chitose ends up being chosen as the pilot of the 6th Angel Frame, the "Sharp Shooter", which is designed for extreme range sniping. Chitose greatly respects her friends/teammates in the Angel Troupe, to the point where she wishes not to do anything that might offend them, even to the point of forcing herself to suppress her growing feelings for Takuto.
Chitose's hobbies include archery and tea. Her 'fish out of water' situation is the source of much comic relief, since she originally believed the Angels and Takuto were model soldiers. The realization that they were all quirky was somewhat of a shock. Among such events include her hyperventilating when asked by Takuto and the Angels to address him by his first name rather than the more official 'Commander Mayers' (prompting Vanilla to tell her to take a deep breath and calm down), fainting after eating one of Ranpha's ultra-spicy Ranpha specials and fainting again upon meeting Empress Shiva in person for the first time. This latter event made Shiva ask Takuto if Chitose would really be okay aboard the Elsior, to which all Takuto could do was give an uncertain, embarrassed laugh.
Originally, Chitose did not have a story in the game, unlike the other Angels. In fact, in every romantic storyline except Milfeulle's, Chitose is an unwitting and unintentional source of conflict (in their respective storylines, Ranpha mistakenly believes Takuto is attracted to Chitose and so does Mint although to a much lesser extent than Ranpha, Forte gets into arguments with her, and she misunderstands the nature of Takuto and Vanilla's relationship as similar to siblings'). In each case, however, Chitose feels awful upon discovering this and enthusiastically supports Takuto's relationship with the one he loves (in fact, in Mint's storyline, Chitose actively tries to help Takuto and Mint make up by going shopping with Tact for the sole purpose of buying Mint a gift to help Tact and Mint reconcile; this is unsuccessful but it indirectly provides the opportunity for Tact and Mint to reconcile by themselves, and Mint much later does make use of the gift Chitose and Tact bought).
However, in the PS2 version of Moonlit Lovers (and a patch for the same story was released with Eternal Lovers for the PC version Moonlit Lovers), she has her own storyline. In it, she takes time adjusting to Takuto's fairly laidback leadership style as she was expecting him to be a model soldier (befitting his reputation as the hero of Transbaal). She eventually becomes comfortable enough to address him as Takuto-san instead of Commander Mayers.
Takuto learns that Chitose's father was a military man who captained a ship and died in an accident when she was young. While saddened, she was proud that he had died doing his duty, the way he'd wanted. However, when Takuto volunteers to help her pilot the super weapon meant to defeat the Val-Fasq warship O-Gaub ravaging Transbaal and is accepted, she attacks and knocks him out just before the launch.
She reveals that she is uncertain that whoever pilots the weapon will survive and while she is willing to die to carry out her duty, she is not willing to see another person she cares for do the same. Takuto manages to convince her otherwise and they manage to destroy the ship. Unlike the other Angels, who are already familiar with Takuto and have accepted her feelings, Chitose keeps hers under wraps. Unbeknownst to her, however, Takuto has begun thinking of her more often as well.
In Eternal Lovers, Chitose and Takuto spend much time together but deny they are a couple. However, the two are attracted to each other, but Takuto is still unsure as to how he feels about her. After urging from most of the crew, Takuto finally admits he's fallen in love with Chitose but is unable to find an opportunity to tell her.
Later still, Takuto is forced to shoot her down to prevent her from falling into enemy hands. As a result of this, Chitose believes herself to be in love with Lester (who, incidentally, happens to match her image of a model soldier). This is to the shock of the Angels and especially Takuto. However, fearing that this is her way of coping with the fact that Takuto was the one to shoot her down, the reluctant hero asks Lester to continue the charade, much to Lester (and Almo's) chargin.
The delusion proves so strong that even when Takuto writes her a love letter, she assumes it is from Lester and that Takuto is merely the messenger. It would not be until after the liberation of EDEN that Chitose (after being taken to the infirmary after a fainting spell) admits that she loves Takuto, who reciprocates. He embraces her, only to have her faint from happiness and embarrassment. Shortly before the final battle with the Val-Fasq, the two meet at the park aboard the Elsior and share their first kiss under the stars.
In Galaxy Angel II, Chitose is one of the two members of the Moon Angel Troupe who does not resign from the military. She is used to stay in the planet "Celdar" along with Forte Stollen. She now stays abroad Elsior and protects the gate in the EDEN universe along with Lester Cooldaras.