Kayo is a 10-year-old girl with a petite physique and distinctive features. She has striking crimson eyes framed by thin eyebrows and thick eyelashes, which give her a gentle yet intense look. Her small lips and tiny nose add to her youthful appearance. Kayo’s blonde hair is kept loose, reaching her nape, with a prominent bang that covers her forehead and extends to the middle of her face. Two larger strands of hair rest above her jawline, stretching below her shoulders, with noticeable joints along the strands, adding to the unique texture of her hair.

She is dressed in a small, brown sweater with knots on the right side, featuring an intricate design around the waist and sleeves. A dark brown turtleneck peeks out from around her collar, with long sleeves that cover her arms. Her lower body is adorned with black, tight-fitting shorts that extend to the middle of her thighs, and she wears small, white shoes to complete her outfit. Kayo’s appearance reflects her youthful innocence and somewhat whimsical style.

Kayo Senju is a quiet and reserved young girl who demonstrates a high level of obedience, particularly towards her Promoter, Shougen Ikuma, despite the fact that he views Initiators like her as mere tools. While she may not speak often, her actions and expressions show that she is capable of understanding and communicating her needs, as seen when she subtly signals her hunger, a detail that Rentaro Satomi notices during a meeting.

Though young, Kayo believes in her own strength as an Initiator and does not shy away from dangerous situations. She has faced several Gastrea without showing fear, and even took charge during a breach of the Tokyo Area, confidently instructing Initiator Enju Aihara to step back as she prepared to confront the Stage II Gastrea on her own. Kayo takes her role seriously and is quick to reprimand anyone who undermines the gravity of her work, showcasing a strong sense of responsibility and determination in her duty to protect humanity from the Gastrea threat.

Kayo worked closely with her Promoter, Shougen Ikuma, as part of their Civil Security team. Their partnership relied on Kayo’s efficiency and combat skills, complemented by Shougen’s leadership and strategy.

Kayo’s abilities as an Initiator made her a key asset in the fight against the Gastrea. Her precise movements and tactical approach to battle allowed her to take on formidable opponents with ease.

Kayo’s partnership with Shougen highlighted the bond between Promoters and Initiators in their shared struggle against the Gastrea, emphasizing the sacrifices and challenges of their profession.

• Shougen Ikuma
  Kayo’s relationship with Shougen was one of mutual trust and professionalism. As his Initiator, she relied on his guidance and leadership while providing unwavering support in battle.

• Other Initiators and Promoters
  While Kayo’s reserved personality limited her interactions with others, her skill and focus earned her respect among her peers.

Kayo Senju’s character exemplifies the strength and sacrifice of Initiators in Black Bullet. Her partnership with Shougen Ikuma highlights the teamwork and trust required to face the Gastrea threat, while her composed demeanor and efficient combat style leave a lasting impression on the series. Kayo’s role serves as a reminder of the hardships endured by Cursed Children and the bonds they form with their Promoters in the fight for humanity’s survival.