Koki Yamoto is a central character in the anime series 'Ninja Slayer'. As a dedicated and skilled ninja, Koki plays a vital role in the ongoing battle against the oppressive forces of the Soukai Syndicate. Driven by a personal vendetta and a strong sense of justice, he uses his exceptional combat abilities to protect the innocent and bring down the corrupt organization. Koki's character is defined by his unwavering determination, strategic mind, and a mysterious past that gradually unfolds throughout the series, revealing deeper connections to the ninja world.