Koby made his debut in the Romance Dawn arc. From a very young age, Koby wanted to become a Marine, but his dreams were put on hold after he accidentally boarded Alvida's ship. Alvida did not kill Koby, instead, she kept him on the ship and made him a cabin boy. Koby had to quietly suffer until he met Luffy, who taught him the importance of fighting for his dreams.
With Luffy's help, Koby was finally able to join the Marines, and pursue his dream. Koby has been involved in some of the biggest incidents in the series, but none of them have had as big of an impact on his life as the time he went to Amazon Lily. Koby was tasked by the higher-ups to go to Amazon Lily to capture Boa Hancock, which was not an easy job at all considering that she is among the strongest characters in One Piece.
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When Koby arrived at Amazon Lily, he had no idea that the Marines would have to face the Kuja as well as the Blackbeard Pirates. The fight between the three groups was chaotic, and it allowed Boa Hancock to turn the Marines and Blackbeard's underlings to stone. The Marines were heavily outnumbered, but after unleashing the Seraphim, the tide began to turn. As many of the Marines were under the effect of Boa's devil fruit, they were susceptible to being destroyed by the Seraphim's attacks. So, Koby had no choice but to order them to stop.
This created an opening, and it allowed Blackbeard to capture Boa, after which, he threatened to kill her. Luckily for Boa, Koby managed to stall the Emperor until Rayleigh's arrival. The right-hand man of the Pirate King had garnered a notorious reputation, and he managed to de-escalate the situation. The time that Koby bought was precious and there is
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