Chika Amatori is a petite girl with short black hair, featuring a prominent ahoge (a strand of hair that sticks up) at the top of her head. She has distinctive violet-purple eyes, which add to her soft and reserved appearance.

As a C-Rank Border agent, Chika wears the standard white trainee uniform. Her version features lighter stripe detailing and pants that are tucked into themselves, which appears to be a common variation among female agents. Over this, she wears a jacket for added coverage and warmth.

Upon advancing to B-Rank and joining Tamakoma Second, Chika adopts a customized combat uniform. Her jacket resembles Osamu Mikumo’s in color and general design but differs in key ways: it has a symmetrical layout without shoulder guards and includes a unique suspender-like strap that starts from her right shoulder, connecting to a horizontal line around her waist. Attached to this line are two holsters positioned on either side of her torso. Her jacket sleeves are lined with thin black stripes that widen at the shoulders, framing the Tamakoma Branch emblem. She also wears her collar folded down, in contrast to Osamu and Yūma’s upright collars. The oversized jacket drapes over her black shorts, and her team’s emblem is displayed on the left side of her chest. Chika’s gloves are longer than those of her teammates, extending over her sleeves, and she completes her uniform with knee-high boots equipped with protective knee pads.

Chika Amatori is a quiet and introverted individual, often seen as timid and reserved. She tends to keep her distance from others, a behavior rooted in past trauma involving the abduction of those close to her by Neighbors. Fearing that forming attachments will only lead to more loss, she isolates herself emotionally, resulting in a small circle of friends.

Despite her withdrawn nature, Chika is patient, focused, and takes her responsibilities seriously. She demonstrates exceptional concentration, particularly in combat scenarios, but struggles with low self-esteem and a limited awareness of her own capabilities. She harbors a strong aversion to harming others, which contributes to her reluctance to use her powers offensively.

Chika’s personality begins to shift after meeting Yūma Kuga and joining the Tamakoma Branch. Through her experiences with Tamakoma Second, she gradually opens up, becoming more sociable and developing greater confidence in herself and her abilities. At her core, Chika is a compassionate and kind-hearted person who values the well-being of those around her, even if she initially lacks the courage to act on it.

Trion Capacity
Chika Amatori possesses one of the highest known Trion capacities in World Trigger, with levels so vast that her output using a basic training Trigger rivals that of a Black Trigger. Her extraordinary Trion gland is considered a rare phenomenon, even by Neighbor standards, and both Border and Aftokrator regard her as a potential strategic asset so much so that Aftokrator’s Hyrein identified her as a candidate to become their next “God,” a being used to sustain their planet’s energy source.

Due to her immense Trion reserves, Chika is capable of modifying or amplifying standard Border Triggers far beyond normal use. Her presence alone is often enough to intimidate opponents in Rank Wars, significantly altering their strategies. Even after her reluctance to harm others became common knowledge, her ability to reshape the battlefield such as destroying cover points and fortifications remains a valuable tactical tool. Additionally, her usage of Lead Bullet enables her to hinder enemies non-lethally, creating opportunities for her teammates to secure victories. These contributions are especially effective when used in conjunction with Osamu’s wire zones, where her firepower and support utility become essential to Tamakoma Second’s strategy.

Mental Block
Despite her overwhelming potential, Chika initially suffers from a psychological block that prevents her from attacking people directly. This trauma stems from the disappearance of loved ones presumably taken by Neighbors and her belief that growing close to others puts them in danger. This fear caused her to avoid asking for help and even freeze during life-threatening encounters. However, over time and especially after receiving encouragement from Yūma and Reiji she begins to confront her fears, eventually gaining the strength to fight more confidently and recognize the importance of her own safety in combat.

Side Effects
Chika is uniquely gifted with two distinct Side Effects, an extremely rare occurrence in the World Trigger universe. These abilities have contributed to her ability to evade capture and survive multiple encounters with hostile forces.

Rinji Amatori
Rinji is Chika’s older brother and one of her primary sources of motivation. His abduction by Neighbors alongside that of a close friend deeply affected Chika and sparked her desire to reach A-Rank in order to participate in away missions to the Neighbor worlds. Rinji had previously entrusted Osamu Mikumo with Chika’s safety, asking him to look after her should anything happen. His disappearance continues to drive Chika’s actions throughout the series.

Osamu Mikumo
Osamu, a close friend of Rinji and Chika’s self-appointed protector, plays a central role in Chika’s life. Following her brother’s disappearance, Osamu was the only person she truly trusted. He is consistently supportive of her, encouraging her to overcome her fears and helping her integrate into Border. Chika holds deep respect for Osamu and relies on his guidance. Their mutual trust forms a key pillar of Tamakoma Second’s strength and cohesion.

Yūma Kuga
Chika and Yūma first meet under a bridge while waiting for Osamu. Initially mistaking Yūma for someone younger due to his appearance, she quickly warms up to him and begins to open up emotionally making him the first person aside from Osamu she confides in. Yūma was also the first to recognize the magnitude of Chika’s Trion capacity. Their bond deepens over time, with Chika teaching Yūma how to ride a bicycle and Yūma continuing to support her growth as both a person and a Border agent.

Chika’s given name, Chika (千佳), is composed of the kanji 千 (chi), meaning “thousand,” and 佳 (ka), meaning “excellent,” “beautiful,” or “good.” Together, her name can be interpreted as “a thousand excellences” or “great beauty,” possibly reflecting her hidden potential and inner strength despite her timid nature.

Her surname, Amatori (雨取), combines 雨 (ama or ame), meaning “rain,” and 取 (tori), meaning “to take” or “to grasp.” The name could be interpreted as “one who catches rain” or “rain gatherer,” evoking a sense of quiet melancholy, gentleness, or subtle power character traits closely associated with Chika’s personality and role in the series.