Killer grew up in the South Blue alongside his childhood friend and captain, Eustass Kid. As a core member of the Kid Pirates, Killer earned a reputation for his combat prowess and loyalty to his crew. His skill and brutality in battle led to his designation as one of the “Worst Generation.” Despite his intimidating moniker, Killer is known to act as a voice of reason within the often chaotic dynamic of the Kid Pirates, balancing Kid’s aggressive tendencies.

During the events leading up to the Wano Country Arc, Killer’s fate took a dark turn. After a failed confrontation with Kaidou, Killer was captured and forced to consume a defective SMILE fruit. This robbed him of his ability to express emotions other than laughter, a cruel side effect of the fruit. Under the alias Kamazo the Manslayer, Killer worked as an assassin for the shogun, Kurozumi Orochi, in Wano Country. His task was to eliminate Orochi’s enemies, but after failing a mission to kill Toko, he was discarded by the shogun and publicly humiliated.

Killer’s appearance is striking and intimidating. He wears a distinctive helmet that conceals his face, with long, wild blond hair flowing beneath it. His muscular physique and his signature pair of rotating scythe-like weapons emphasize his fearsome combat style. After consuming the defective SMILE fruit, Killer’s uncontrollable laughter adds an unsettling element to his presence.

Despite his fearsome reputation, Killer is one of the more level-headed members of the Kid Pirates. He often advises Kid and tries to temper his captain’s impulsive behavior. However, the forced consumption of the SMILE fruit drastically affected his demeanor, stripping him of his ability to express emotions other than laughter. This experience, coupled with his humiliation in Wano, further demonstrates his resilience and loyalty to his crew.

Pre-Timeskip
Killer is introduced as a prominent member of the Kid Pirates and one of the “Worst Generation.” His bounty of Beli162,000,000 reflects his strength and notoriety as a pirate.

Wano Country Arc
Following the Kid Pirates’ defeat by Kaidou, Killer was captured and forced to eat a defective SMILE fruit, resulting in his uncontrollable laughter. Under the alias Kamazo the Manslayer, he became an assassin for Kurozumi Orochi but was discarded after failing to complete a mission. Killer later reunites with his crew and joins the Ninja-Pirate-Mink-Samurai Alliance, playing a significant role in the battle against Kaidou and the Beasts Pirates.

• Eustass Kid
  Killer is Kid’s childhood friend and closest ally. He acts as a loyal right-hand man, often providing counsel to Kid despite his captain’s fiery temperament.

• Ninja-Pirate-Mink-Samurai Alliance
  Killer becomes a reluctant yet crucial ally to the alliance during the Wano Country Arc, aiding in their fight against Kaidou and the Beasts Pirates.

• Kurozumi Orochi
  Killer briefly served as an assassin under Orochi’s command but was discarded after failing a mission, marking the end of his forced allegiance.