Roronoa Zoro is a pirate, former bounty hunter, and one of the main protagonists of One Piece. He was the first member to join the Straw Hat Pirates, and to date is considered the largest threat and most dangerous member in the crew after the captain Luffy. He is famed as a master swordsman, user of the Santoryu style
(3 Swords), and his great strength (and the actions of his captain) sometimes leads others to believe he must be the true captain. Being labeled as one of the "Monster Trio", he's one of the top three fighters in the crew. His dream is to become the greatest swordsman in the world. Zoro was labeled as one of "The Eleven Supernovas", the eleven rookie pirates with bounties over 100,000,000 beli to have reached the Red Line.

Ikkaku Madarame is the 3rd Seat of the 11th Division in the Gotei 13. His captain is Kenpachi Zaraki. In terms of his attitude, Ikkaku is a stereotypical 11th Division member — violent, fight-loving, and rude. This has been noted by Tetsuzaemon Iba, among others. He loves fighting so much that he is unwilling to travel anywhere without a sword, resorting to carrying a wooden one when posing as a student at Ichigo Kurosaki's school. However, Ikkaku does have a sense of loyalty and responsibility unlike many of the lower-ranked 11th Division members and is fiercely loyal to his captain, under whose command he wishes to die..

Sousuke is an approximately 17 year old sergeant within the paramilitary counter-terrorist force, Mithril. He is a member of the SRT (Special Response Team) of the Western Pacific Battle Group "Tuatha de Danaan". His call sign is Uruz-7 and his ID number is B-3128, and operates as team point-man as an Arm Slave specialist.
In addition to being a capable Arm Slave pilot, Sousuke is a specialist in Arm Slave operations and maintenance, improvised explosives, small arms, survival training, anti-armor combat, trap setting and camouflage. Additionally, he is proficient in logistics, demolitions, breach and forced entry, covert intrusion, and hand to hand combat. His background and experience as a guerrilla fighter, and later a mercenary soldier has made him much more sensitive and knowledgeable about tactics and methods more commonly used by guerrillas than government trained regulars.

Hiei is a male fire demon born to a race of female ice demons. His mother, Hina, is forced to abandon him because koorime prohibit male children. Hiei is taken in by a group of thieves, and he learns to kill at a very young age. Throughout his childhood, his one shred of sanity is a necklace made from his mother's hiruiseki (氷涙石, ice tear stone). He eventually loses the necklace in the heat of battle. In order to find the lost hirui, Hiei acquires the Jagan. He uses the Jagan to seek out the place of his birth and learns that his grief-stricken mother committed suicide; Hiei also learns that he has a twin sister, Yukina, who has disappeared from the village. He now has another goal, to search for Yukina. Hiei is aloof, elusive, and misanthropic, often belittling and mocking humans and their emotions.