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Kayo Senju

(かよ せんじゅ)


Kayo Senju


Cursed Child






Female.png Female





Hair Color

Light Blue (Manga)
Blonde (Anime)

Eye Color


Professional Status
Previous Affiliation

Civil Security Corporation

Previous Occupation


IP Rank


Previous Partner(s)

Shougen Ikuma (deceased)

Base of Operations

Mika Island Civil Security Corporation (formerly)

Personal Status






Manga Debut

Chapter 5

Anime Debut

Episode 2

Japanese Voice

Megumi Han

Image Gallery

"Don't scream so loudly. I know."

— Kayo Senju in "The Beginning of the End"

Kayo Senju (千寿 夏世, かよ せんじゅ, Senju Kayo) was an Initiator partnered with Shougen Ikuma.


Kayo in color.

Kayo was a 10 year old girl with a small physique. Her face is gifted with thin eyebrows and thick eyelashes that arch around crimson eyes, as well as small lips and a tiny nose. She keeps her blonde hair loose at the back, reaching to her nape. A moderate-sized bang, covering her forehead and elongating to the middle of her face; in between her eyebrows, lies present. Two hefty strands of hair, positioned above her jawline and stretching below her shoulders, are noted to be joint in several locations and left untouched towards the strands' tips.[1]

Kayo dons a small, brown sweater, with multiple knots on the right side, as well as an intricate design around the waist and sleeves. Encompassing her collar is a dark brown turtleneck jutting outwards, and long sleeves that cover her arms. Covering partial parts of her legs are tight, black shorts that elongate to the middle of her thighs. She walks around in small, white shoes.[2]


Kayo Senju is a silent young girl that appears to be rather obedient to Shougen Ikuma,[3] her Promoter; despite the latter thinking of the Initiators as nothing more than mere tools.[4] She also displays clear indications when she desires something, such as the time when Rentaro Satomi was quick to notice that she was hungry whilst attending the meeting they were summoned to by Seitenshi.[1] Kayo believes in her strength as an Initiator, confronting several Gastrea without showing signs of fear,[5] and even to the point of ordering Initiator Enju Aihara to stand back when the Tokyo Area is breached by three Stage II Gastrea, claiming that she alone will annihilate the parasites.[6] She takes her job as an Initiator extremely serious, as she bashes the ones that make light of it.[7]


The Cursed Children arc[]

Kayo catches Shougen's sword.

After Shougen's spectacle at Seitenshi's meeting, Kayo stands next to him, and notes Rentaro Satomi, the boy Shougen attacked, is looking at her. She rubs her belly and admits that she is hungry whilst blushing. When the meeting gets underway, Kayo listens to Seitenshi's orders: to kill the Gastrea that invaded the Tokyo Area, and retrieve a case that is thought to be inside its belly. Shortly thereafter, she and the others in the room are interrupted by a booming laugh, turning out to come from Kagetane Hiruko, who announces their presence and names himself an enemy of Civil Security. Kayo quickly picks herself up and helps Shougen when the man, annoyed, attacks the masked figure. However, their efforts are futile as Kagetane's Repulsion Shield blocks all attacks thrown at him. When Kagetane finally leaves after causing an uproar, Kayo looks at the present he left behind, disgusted by the contents: President Oose's head. She then returns her attention to Seitenshi as she is forced to reveal the truth about the Legacy of the Seven Stars.[8]

Legacy of the Seven Stars arc[]

Kayo smiles at Rentaro.

On a rainy day, Kayo and Shougen look around a forest for the case, only to come across Enju Aihara, who desperately begs them for help. The two follow her steps and find Rentaro heavily wounded, quickly taking him to the hospital.[9] A day and a half later, Kayo finds Rentaro and Enju near the place of departure. She watches as Rentaro and Shougen begin to argue, but then grabs her Promoter and reminds him that they must get ready for departure. As she walks away, she winks at Rentaro with a smile on her face.[10]

Kayo finds Enju.

After arriving to the Unexplored Territory, a visibly injured Kayo, holding a gun to Enju's head, questions her identity whilst shaking violently.[11] Kayo can only sit quietly as Rentaro tends to her injuries, only to be asked by the young Promoter if she is okay, to which she responds affirmatively. As she informs him that the injury should heal pretty soon, she states that she is Shougen's Initiator and tells him her name.[12] When Rentaro attempts to introduce himself as well, Kayo interrupts him and claims that she knows who he is; turning her attention to Enju, whom she unintentionally angered. She explains to Rentaro, who is still pondering Enju's motives, that Enju's sudden mood change towards her should be obvious.[13]

Kayo's reaction to Rentaro's dullness.

Moments later, Rentaro questions the contents inside the case next to Kayo, causing her to place a hand over it and refuse to reveal anything for several minutes. Nonetheless, she decides to open it and display its contents; angering Rentaro as he bares witness to several explosives inside. She is continuously questioned, only to tell the boy that, having been attacked by a strange Gastrea to her eyes, she accidentally used an explosive without a second thought. She listens to Rentaro's hypothesis and calls him intelligent as he ends his claim, with the latter slightly agitated by the compliment. Laughing at Rentaro's shyness, she admits that she is jealous of Enju, only to be asked by Rentaro if she is happy with being Shougen's Initiator. However, Kayo solely informs Rentaro that to Shougen, the Initiators are nothing more than mere tools for killing; corrected by Rentaro minutes after.[14]

Kayo addresses Rentaro.

Watching as Rentaro clenches his fist, she questions if he has ever killed someone before, informing him that she has. Seeing as he is visibly angered by her claim, Kayo begs him to keep calm, as he has done the same. She continues to express herself and tell Rentaro that when humans see Gastrea, all they can think about is murder, and that it is an Initiator's job to kill the Gastrea lingering about. When Rentaro asks her if the fact that a Promoter's orders are absolute does not bother her, she replies shallowly; claiming that it will not change anything. Grabbed by Rentaro and pinned to the ground sequentially, Kayo listens to Rentaro as he informs her of the time Enju nearly killed a Promoter that fell into darkness; Enju was greatly depressed. He continues to tell her that Initiators are humans and family. However, she interrupts him when she tells him that his words are just "pretty," reminding him that if she were truly his family, he would not let her bare the full brunt of a battle. Albeit, placing her hands in front of his face, tells him that she does not want to deny his words. With Rentaro looking at her as she continues, she inquires him to let his eyes be lit by a strong light as he is righteous. Shortly thereafter, she asks him to get off of her.[15]

Kayo reveals her model.

Sitting next to Rentaro, Kayo speaks about the time when the Gastrea war first began, calling it a cruel world. She tells him that although she did not experience what the "pure" generation did, many have been witness to the Gastrea's uprising. She points to Heaven's Gate and notifies him that it was born from the great Gastrea war. She process to talk about the new human creation plan, only to hear Rentaro state that using the power similar to Kagetane's is what a coward would do. Kayo suddenly gets a call from Shougen, pushing Rentaro aside as she answers. She is told by the Promoter that they have found the masked man. She packs her stuff and gets ready to leave with Rentaro and Enju. Along the way, feeling that Rentaro is thinking about her, she kicks the boy in his back. The three soon arrive to their destination and are ambushed by a deer-like Gastrea. However, Kayo makes quick work of it with her weapon. As several other Gastrea appear, she claims that Cogitation is her power; the Gastrea behind her falling into the ground. She places her weapon on her back and reveals that she is model Dolphin.[16]

The group hears a loud roar.

Kayo speaks to Shougen on the phone, who gets ready to attack Kagetane, as Rentaro stands to her side, listening. She is quickly informed by the man that they will proceed with the ambush, revealing that several Civil Securities have gathered around.[17] Shortly after hanging up, she hears Rentaro's thoughts about her model, but interrupts him as she urges him to the port; she will stay behind to prevent Gastrea from entering the area. Rentaro is left dumbfounded as she tells him that at the scene there are groups stronger than she and Shougen, leading the young Promoter to wonder if she would be of more help; suggesting he stays behind. However, Kayo slaps him, reminding him that he is of Civil Security and that they did not come to play comrades. She is then asked by Rentaro if she is simply asking for them to leave her behind.[18]

Kayo tells Rentaro that she will not die.

Kayo responds rather rapidly, informing him that Shougen would have already left her behind, or even gotten a new Initiator if she were to die. Rentaro, enraged by her words, questions if she does not wish to live a normal life as a human, only to be told that she will not attempt to change his way of viewing Shougen, but tells him that she never said she would die. As she walks towards the forest with her gun, she asks Rentaro to look after Shougen, despite his evident dislike for the latter.[19]

After Rentaro defeats Scorpion and exits the Ladder of Heaven, he finds Kayo injured and sitting against a rock while Gastra remains were everywhere. Kayo didn't end up running and fought the Gastrea, though this caused her to go above the 50% contamination threshold and start to transform into a Gastrea. Knowing this, she asked Rentaro to kill her while she was still human, and Rentaro grants her that wish, even though it pained him to do so.[20]


Initiator (イニシエーター Inishiētā): Controlling the Gastrea blood in her body, Kayo has gained superhuman abilities; thus becoming a member of Civil Security and receiving a Promoter as her partner.[21] She is a Model Dolphin Initiator, which gives her a higher intellect than most.[22]

Kayo's agility.

  • Initiator's Ability: Physique: As a carrier of the Gastrea blood, Kayo is gifted with supreme physique. Such feat is proven when the young Initiator jumps into the air and easily kicks Shougen's Buster Sword with her foot, and with little to no effort at all, reaching the destined location in mere seconds.[23]
  • Initiator's Ability: Agility: Kayo has incredible speed, granted to her by the Gastrea blood inside of her body. She was able to rush to where Shougen's sword had been sent to in just a few seconds, causing the objects behind her to lose their position due to the pressure of her momentum. Additionally, she was able to quickly change her body position to kick the sword with her foot rather rapidly in midair.[3]
  • Initiator's Ability: Recovery: As an Initiator, Kayo possesses superior recovery speed.[24] However, Kayo has demonstrated premature healing abilities in comparison to those of Enju's.[13]


Lupara: Kayo seems to be very proficient when it comes to using her signature weapon, a Lupara. The Lupara itself is identical to a man-crafted Lupara, with a dark body and lighter sides. When utilizing it in combination with her cogitation, Kayo proves to be extremely skillful, defeating a Gastrea in a single shot.[25][26]


Appearances in Other Media[]


A Day of Civil Securities[]

Kayo witnesses Enju's strength.

Kayo comes crashing down from the sky alongside Shougen when they spot a man transforming into a Gastrea. They quickly defeat it and, noticing Rentaro's presence, comment on his lack of responsibility. Kayo looks down at him and questions what Civil Security member talks so nicely to a Gastrea when Rentaro argues that they took his opponent. She continues to confront him by asking for his Initiator's whereabouts, explaining that each Civil Security should have a Promoter and Initiator. She then tells him that he is making light of their work for thinking that he can defeat a Gastrea without the help of an Initiator, rapidly asking what happened to Enju. Before he can answer, however, she is told by Shougen to ignore him, which she does as she turns her head and leaves the vicinity.[36] Shortly thereafter, she appears in front of multiple Gastrea and gets ready to fight them when, suddenly, Enju and Rentaro appear. At first, Kayo tells her to stand back as she is not strong enough to fight the Gastrea in front of them. However, she stays silent when Enju kills one in a matter of seconds. The four, leaving their differences aside, ready to battle the Gastrea.[37]

Battles & Events[]




  • The name Kayo means "summer" (夏) (ka) and "world" (世) (yo).
  • Kayo's surname Senju means "thousand" (千) (sen) and "longevity" (寿) (ju).


  1. 1.0 1.1 1.2 Black Bullet Manga: Chapter 5, Page 6
  2. Black Bullet Manga: Chapter 5, Page 5
  3. 3.0 3.1 3.2 Black Bullet Manga: Chapter 5, Pages 24-25
  4. Black Bullet Manga: Chapter 5, Page 3
  5. Black Bullet Omake: A Day of Civil Securities, Page 9
  6. Black Bullet Omake: A Day of Civil Securities, Page 11
  7. Black Bullet Omake: A Day of Civil Securities, Page 4
  8. Black Bullet Manga: Chapter 5, Pages 5-39
  9. Black Bullet Manga: Chapter 9, Pages 13-14
  10. Black Bullet Manga: Chapter 9, Pages 37-39
  11. Black Bullet Manga: Chapter 10, Pages 14-15
  12. Black Bullet Manga: Chapter 11, Page 2
  13. 13.0 13.1 Black Bullet Manga: Chapter 11, Page 4
  14. Black Bullet Manga: Chapter 11, Pages 4-11
  15. Black Bullet Manga: Chapter 11, Pages 12-18
  16. Black Bullet Manga: Chapter 11, Pages 19-32
  17. Black Bullet Manga: Chapter 12, Page 1
  18. Black Bullet Manga: Chapter 12, Pages 3-5
  19. Black Bullet Manga: Chapter 12, Pages 6-9
  20. Episode 4
  21. Black Bullet Manga: Chapter 2, Pages 35-36
  22. Black Bullet Manga: Chapter 11, Page 33
  23. Black Bullet Manga: Chapter 5, Page 25
  24. Black Bullet Manga: Chapter 2, Page 28
  25. Black Bullet Manga: Chapter 10, Page 15
  26. Black Bullet Manga: Chapter 11, Pages 29-30
  27. Black Bullet Manga: Chapter 11, Page 10
  28. Black Bullet Manga: Chapter 11, Page 14
  29. Black Bullet Manga: Chapter 11, Page 25
  30. Black Bullet Manga: Chapter 12, Pages 16-18
  31. Black Bullet Manga: Chapter 9, Page 39
  32. Black Bullet Manga: Chapter 10, Page 15
  33. Black Bullet Manga: Chapter 11, Pages 10-18
  34. Black Bullet Manga: Chapter 11, Page 26
  35. Black Bullet Series: Episode 4
  36. Black Bullet Omake: A Day of Civil Securities, Pages 2-3
  37. Black Bullet Omake: A Day of Civil Securities, Pages 9-13
  38. Black Bullet Omake: A Day of Civil Securities, Pages 11-12