Chika Amatori is a young girl with short black hair and purple eyes. She is a B-rank Sniper and a member of the Tamakoma Second unit. Her most defining characteristic is her extraordinarily immense trion level, which is so vast that it is considered to be on par with a Black Trigger. This immense power is a double-edged sword: for years, it caused her to be a constant target for Trion Soldiers and Neighbors seeking to kidnap her to use her as a power source.

Chika's background is marked by traumatic losses directly related to her unique ability. Her friend Aoba Harukawa was taken by Trion Soldiers, and later her brother, Rinji, also disappeared. She blames herself for these incidents, which led her to voluntarily distance herself from others out of a fear that anyone she grows close to will be hurt or kidnapped because of her. This trauma has made her naturally timid, withdrawn, and soft-spoken. She is a patient, serious, and kind-hearted individual who can concentrate exceptionally well, but she also suffers from low self-confidence and struggles to recognize her own enormous potential.

Her primary motivation is to become strong enough to travel to the Neighbor world to search for her missing brother. She enlists the help of her friend and teammate, Osamu Mikumo, to achieve this goal. Meeting Osamu and the Neighbor Yuma Kuga, and subsequently joining the Tamakoma Branch, becomes a turning point for Chika. Being part of this small, close-knit unit helps her gradually begin to open up, become more sociable, and slowly build her confidence.

In combat, Chika fulfills the sniper role for Tamakoma Second. Her primary contribution is her sheer, overwhelming firepower. Her sniper shots, particularly with the heavy Ibis rifle, are so powerful that they are dubbed the Amatori Cannon, capable of leveling buildings and dramatically reshaping the battlefield. She has access to multiple sniper triggers, including Egret and Lightning, but her true value lies in her ability to use the optional Lead Bullet trigger. Lead Bullet negates a shot's killing power in exchange for generating heavy weights that can pin down or paralyze an opponent. Since her trion reserves are so massive, she can overcome the usual speed penalties associated with Lead Bullets, making them a highly effective tool for disabling enemies without destroying their trion bodies.

A crucial aspect of her character arc is her deep-seated psychological block against harming others. For a significant portion of the story, Chika is terrified of shooting at human opponents, which severely limits her combat effectiveness in rank wars. Her kind nature makes her unable to willingly inflict pain or bail out another person, a major weakness for a combat agent. However, her development as an agent and a person centers on confronting and overcoming this fear. She learns to use Lead Bullets as a workaround to contribute without causing direct harm, and eventually, she begins to move past her trauma, finding the resolve to shoot at opponents when absolutely necessary.

Chika also possesses a unique side effect, a rare ability separate from normal trion organs. She has the power to conceal her presence from Trion Soldiers by calming her mind and emptying her thoughts. Conversely, she can also sense the approach and location of inbound Neighbors, making her an invaluable asset for detection and early warning. Despite her mental blocks, she is a gifted sniper trained by some of Border's best. She is disciplined, has high stamina, and is a steady and painstaking worker, all qualities that make her exceptionally suited for the patient and precise role of a sniper.