Yamoto Koki

Yamoto Koki

Yamoto Novel 2

Yamoto Novel 3

Yamoto manga color

Yamoto GK

Koki Yamoto anime design

Kanji: ヤモト・コキ
Romaji: Yamoto Koki
Status: Alive
Gender: Female
Affiliations: Nichom Council
Relatives: Unnamed Parents (deceased)

Yamoto Ishii (unknown relation)

Voice Actor: Amamiya Sora (Japanese)

Monica Rial (English)

Novel Debut: Last Girl Standing
Manga Debut: Chapter 5
Chapter 6 (Glamorous Killers)
Anime Debut: Episode 3
Image Gallery

Yamoto Koki (ヤモト・コキ) is a high-school girl and ninja. Her ninja soul is the Shi Ninja (シ・ニンジャ).


Yamoto poster
Yamoto has short black hair and blue eyes. She wears a Japanese school sailor uniform that's white and black. When using Shi Ninja's power, her eyes turn purple and a ghost-like purple scarf forms on her. She also wears a black winter coat.

In the past, Yamoto is shown to have longer hair.


Yamoto a reserved girl and is shown to care deeply for her friends and against joining the Soukai Syndicate. She is shown to turn violent when using Shi Ninja's power and finds enjoyment in it, however, she has since gained better control over it. Yamoto also speaks using the first person pronoun "アタイ Atai, Me is[1] " which is done to show Shi Ninja's influence on her. However, she sometimes breaks free and use "私, Watashi", which is what most Japanese girls use.


The history's timeline is shown in order of events, not order of release.

Part 1: Neo-Saitama in Flames Edit

Past Edit

She was said to have killed her parents by Sonic Boom.

Last Girl Standing Edit

Sometime in the past, another student, Shogo Maguchi, attempted to commit suicide by jumping on the school roof and landed on Yamoto. At the brink of death, Shi Ninja had entered her body and kept her alive.

Yamoto 2nd fight

Yamoto using her origami weapons during her fight with Sonic Boom.

Some time later, Yamoto and her friend, Asari, are attacked, and as Yamoto is being choked, Shi Ninja calls out to her. Yamoto then uses Shi Ninja's power to defeat her attackers and save Asari. During the fight, Yamoto takes pleasure in hurting the people and at first states that wasn't her own thoughts, but quickly realizes these were her thoughts at the time. Yamoto's new found strength makes people no longer bother her in school. The Soukai Syndicate, aware of Yamoto's ninja soul, orders the newly added member Shogo, who was renamed Suicide by Sonic Boom, to kill her.

While she is at a karaoke with her friends, Shogo gets her attention and apologizes for what he had done to her, and attempts to hold back Sonic Boom so she could escape with her friends. Sonic Boom proves too much for Shogo and soon after begins to fight Yamoto. Sonic Boom also seems to be too much for her as he overpowers her, however she is saved by Ninja Slayer. After Ninja Slayer fights with Sonic Boom for a while, Yamoto delivers the final blow on Sonic Boom with a large origami attack, which kills him. Even though Ninja Slayer's soul, Naraku Ninja, insists on killing Yamoto, Ninja Slayer refuses, letting her escape.

Seven days after this, Yamoto goes to Asari's window, apologizing for getting her in bad situations and says sayonara, and that she'll be there if Asari ever needs her help. She then jumps away.

Swan Song Sung by a Faded Crow Edit

Days later, Yamoto meets Kagi Tanaka at a laundromat. Surprised by seeing a teenage girl in such place so late in the night, he tries to start a conversation and then goes out, leaving Yamoto alone. She then gets attacked by Nutcracker and is saved when Kagi stabs him, killing him. She then comes under protection of Kagi as he teaches her karate.

The Soukaiya sends their ninja soul tracker, Third Eye, and mercenary Sword Dancer to kill Yamoto, along with ordering Kagi to kill her too. She fights and kills Third Eye and appears before Silver Karasu, and recognizes him as Kagi right away. She half-hardheartedly fights him, then cries as she could not seriously fight and try to kill her sensei. Kagi then dies to his cancer in front of Yamoto.

She is later seen escaping Clone Yakuza by jumping onto a moving train and then opens a pack of Kagi's cigarettes.

Treasure Every Meeting Edit

Yamoto happy

Yamoto says goodbye to Genocide.

Yamoto wanders into a church, exhausted, and meets Genocide, a zombie created by Yoroshisan's Dr. Lee Araki, and ends up befriending him. Genocide buried an old lady who had died recently and had said "Shi Ninja" when he saw Yamoto. Dr. Lee sends Clone Yakuza, a new experiment Manticore, and a Soukaiya ninja named Grenadier to kill him. Yamoto and Genocide fight them off and win. Yamoto then sets off and Genocide tells her not to hold it against him if they meet again as he might not remember her because he has a rotting brain and forgets things easily.

Neo-Saitama in Flames (anime only cameo) Edit

After Laomoto Khan's death at the hands of Ninja Slayer, she is seen cornered by Clone Yakuza while Soukaiya buildings are burning.

Part 2: Kyoto: Hell on Earth Edit

Kickstart a New Day Edit

Welcome to Neo-Saitama Edit

Waiting for My Ninja Edit

Physician, Heal Yourself Edit

Siege to the Sleeping Beauty Edit

Part 3: Ninja Slayer Never Dies Edit

Satsubatsu Night by Night Edit

Yamoto Satsubatsu

Yamoto doing her aisatsu in Satsubatsu Night by Night.

Death Trap, Suicide Rap Edit

Nichom War...Beginning Edit

Shock to the System Edit

Farewell My Shadow Edit

Nichom War Edit

Unveil The Trail Edit

Ninja Slayer: Never Dies Edit

Part 4: Age of Mappor-Calypse Edit

Dead! Deader than Dead! Edit

For Whom the Bell Tolls Edit

Power & AbilitiesEdit

  • Sakura Enhancement Jitsu: She can enhance an object touching the hand, and turn it into bomb by injecting energy into the object.
  • Origami Missile (Origami Suriken): Sakura Enhanced origami projectiles.
  • Karate: Uses karate as taught to ber by Silver Karasu.
  • Iaido: She was trained by Silver Karasu and uses his sword.

Relationships Edit

Kagi Tanaka Edit

Her sensei and guardian.

Genocide Edit

An escaped Yoroshisan bio-ninja zombie she meets and befriends.

Asari Edit

Her best friend from high school.

Ninja Slayer Edit

He helped her defeat Sonic Boom.

Trivia Edit

  • The high school she attended was called Atabaki Bushido Highschool (アタバキ・ブシド・ハイスクール, Atabaki Bushido Haisukūru).
  • She is 153 cm tall in Parts 1-3, and 157 cm tall in Part 4.
  • There is a serial killer with a ninja soul named Killcharge (キルチャージ, Kiruchāji), whose real name is Yamoto Ishii (ヤモト・イシイ). It was said they are possibly immediate family to Yamoto.[2]


References Edit

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