karasuma chitose

In the anime
Karasuma Chitose is a frail girl who joined the Galaxy Angels upon request. Despite her polished and affectionate demeanor, she often proves socially awkward and occasionally bloodthirsty.
For most of her first 17 years, Chitose was hospitalized due to an incurable illness. Having no friends, she spent her days in her room watching healthier people play outside through her window and counting leaves on a nearby tree. The Angels visited her as a gesture of goodwill, during which she collapsed and pleaded to join them before her death. Her wish was granted.
However, once among the Angels, Chitose's lack of tact prevented her from making friends and led to her being ostracized by most members. Feeling rejected, she vowed to destroy the Angels and joined their rivals, the Galaxy Twin-Stars, as part of her revenge plan. This initiated a one-sided antagonism between Chitose and the Angels, with Milfeulle still considering her a good friend while others either forgot her or became indifferent. She was later reassigned back to the Angels, attempting friendship and destruction simultaneously.
Though generally kind and sweet, Chitose oscillates between wanting to befriend the Angels and wanting to kill them. Her incompetence and bad luck often result in self-harm rather than harm to others. Unfortunately, her ability to make friends is similarly hindered, leading to further self-injury and renewed determination for vengeance. Ultimately, she rejoins the Angels.
After serving 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 never been more miserable.

In the manga
She is the newest member of the Angel Troupe. Found drifting in space in an escape capsule, she was the sole survivor of a destroyed ship. Upon exiting the capsule, Chitose lost most of her memory. With help from the Angels and Takuto, she gradually recovers her memories. As Takuto aids her recovery, she starts developing feelings for him. The other Angels grow concerned about Milfieulle and Takuto's relationship, but Milfie assures them it's not a big deal since she wants Chitose's memory to fully return.
However, in volume 2, it is revealed that Chitose has unknowingly been under Noa's mind control all along. Noa attempts to have Chitose kidnap Prince Shiva, but Chitose regains enough of her own will to instead kidnap Takuto.