Koby

Koby is a Marine Captain who, like Helmeppo, trained under Vice Admiral Garp. He is a member of SWORD, a special forces unit within the Marines. In his early days, he was a caretaker for the Alvida Pirates until he was rescued by Luffy, who later became his friend. Koby is known as a hero for his actions during the Rocky Port Incident and became a fully-fledged Marine soldier by the time of the Post-Enies Lobby Arc. In the Diary of Koby-Meppo Cover Page Serial, Koby and Helmeppo are the main characters. They are also the supporting antagonists of the Post-Enies Lobby Arc. During his initial appearance, Koby lacked any fighting skills and was only useful for his navigation abilities. However, his training under Garp and further development during the two-year timeskip has granted him immense physical strength, speed, and the ability to swim quickly. He has some knowledge of swordsmanship, which he practices with Helmeppo and Bogard.

Koby has risen to the rank of captain and is in charge of his own ship and lower-ranking Marines. He played a role in the Marines' attempt to arrest Boa Hancock, where he was one of the few Marines not turned to stone. However, he was captured by Marshall D. Teach and is currently a prisoner of the Blackbeard Pirates. While Koby possesses great strength and skill, he is no match for powerful foes like Boa Hancock or Marshall D. Teach. In Episode of Luffy, Koby demonstrated his impressive strength by shattering a massive metal disk with a single punch and easily executing Rokushiki techniques, including the Soru technique, which he learned from Vice Admiral Garp. Although he utilized Soru against Luffy twice, once in Water 7 and again at the Summit War of Marineford, it did not give him an advantage in either fight. In One Piece: Gigant Battle! 2 New World, Koby also demonstrated the ability to use Geppo and Rankyaku techniques. After the time-skip, Koby has honed his Rokushiki techniques to mastery level, even demonstrating a technique similar to Rankyaku using his arms in Episode of Luffy. He also awakened his Kenbunshoku Haki during the Summit War of Marineford, allowing him to sense the deaths of combatants around him. Since then, he has developed his Kenbunshoku Haki to an advanced level, as demonstrated by his ability to detect a torpedo heading towards a ship from a distance and sense Kyros's immense strength upon first meeting him.

Furthermore, Koby possesses the ability to use Busoshoku Haki. Following the Seven Warlords of the Sea system's abolition, Koby embarked on a mission to capture Boa Hancock in Amazon Lily. En route, he contacted X Drake through the Den Den Mushi, who informed him of the newly formed alliance between Kaido and Big Mom and CP0's arrival in Wano Country. With the aid of the new Seraphim, the Marines battled their way into Amazon Lily. However, when the Blackbeard Pirates also launched an invasion, Koby ordered S-Hawk to cease fire as it endangered the Marines. Despite Koby's demand that Hancock surrender to the Marines, the Empress refused and attacked, petrifying most of the Marines and pirates present. Teach took advantage of the situation and seized Hancock, neutralizing her powers. Although Koby attempted to negotiate Hancock's release, Teach refused to trust her, and Silvers Rayleigh intervened as a mediator. Eventually, Hancock was freed and restored the petrified individuals. The Marines and Blackbeard Pirates departed from the island, but news later surfaced that the Blackbeard Pirates had abducted Koby.