Young Samurai

• Jack Fletcher – protagonist of the Young Samurai series. Shows affection for Akiko and cares deeply for her.
• Dāte Akiko – daughter of Dāte Hiroko and niece of Masamoto. A master warrior. Gives Jack a black pearl in Way of the Dragon. Shows a lot of affection for Takuan Nakamura and Jack Fletcher in Way of the Dragon.
• Yamato – second-born son of Masamoto. Feels like his father does not love him.
• Masamoto Takeshi – samurai swordmaster and founder of the Niten Ichi-Ryū school. Banished by Kamakura at the conclusion of Way of the Dragon, returns as a messenger in Ring of Sky.
• Dokugan Ryu (Hattori Tatsuo) – one-eyed ninja and Jack's sworn enemy. The main antagonist in the series. Once a daimyō of Japan's Northern Province and defeated. Dies in Way of the Dragon...
• Sensei Hosokawa – sensei of Kenjutsu. Dies defending Sensei Yosa in Way of the Dragon.
• Oda Kazuki – student rival of Jack. Revealed to be a Red Devil serving Kamakura in Way of the Dragon, exiled and stripped of all status in Ring of Sky.
• Sensei Kyuzo – sensei of Taijutsu. Has a personal hatred for Jack, but his loyalty to Masamoto is undeniable. Commits ritual suicide in Ring of Sky.
• Saburo – the talkative friend of Jack, who loves eating.
• Kiku – student at the Niten Ichi-Ryū and friend of Akiko.
• Takatomi Hideaki – Daimyō of Kyoto and helps govern Japan on behalf of the future ruler. Becomes regent in Ring of Sky.
• Sensei Yamada – sensei of [Zen], currently accompanying Yori.
• Yori – the quiet, mouse-like friend of Jack, who has a profound ability for Kiai-Jutsu.
• Sensei Yosa – sensei of Kyujutsu, female
• Father Lucius – Portuguese Jesuit priest, in poor health and died early in the series. He taught Jack Japanese.
• Takuan Nakamura – Sensei Nakamura's son, a student at the Niten Ichi-Ryū. Is killed by Dragon Eye's poison dart.
• Tadashi – student at the Niten Ichi-Ryū. He cheated in the Circle of Three by attempting to sabotage Jack and friends.
• Sensei Kano – blind visiting Bojutsu teacher from Mugan Ryu, the Niten Ichi-Ryū's sister school. Ace in a fight against Dragon Eye, carries a white bo staff.
• Emi – Daimyō Takatomi's daughter, a student at the Niten Ichi-Ryū. Used to have a slight crush on Jack.
• Moriko – Kazuki's girlfriend, a student at Yagyu Ryu. Burned and crushed by a falling building.
• Raiden – Kazuki's cousin, a student at Yagyu Ryu.
• Toru – Raiden's twin brother, a student at Yagyu Ryu.
• Nobu – a friend of Kazuki
• Hiroto – a friend of Kazuki
• Goro – a friend of Kazuki
• Father Bobadilla – Portuguese Priest, allied with Dokugan Ryu, killed by his Death Touch.
• Hasegawa Satoshi – the rightful ruler of Japan, committed seppuku in Way of the Dragon.
• Sensei Nakamura – sensei of haiku-writing, female. Perished fighting in Way of the Dragon.
• Jiro – Akiko's little brother, stays in Toba for the series and is re-introduced in Way of the Dragon.
• Kamakura Katsuo – power-hungry daimyō of Edo (Tokyo). Becomes Shogun at the end of Way of the Dragon. Hates foreigners, especially Christians. Dies in Ring of Sky. Attacked Osaka Castle in Way of the Dragon.
• Masamoto Tenno – first-born son of Masamoto, murdered by Dokugan Ryu in the prologue of the Way of the Warrior.
• John Fletcher – Jack's father and navigator of the Alexandria, murdered by Dokugan Ryu early in the series.
• Jess Fletcher – Jack's sister, mentioned but never actually seen throughout the series. She is to be introduced in the 9th Young Samurai book, to be released in 2019.

• Soke – Ninja Grandmaster, and former teacher to Dragon Eye. Took Jack in after realising his plight and hoped to make amends.
• Hanzo – real name Kiyoshi, is Akiko's younger brother. Taken by Dragon Eye during his assault on Tenno.
• Miyuki – expert kunoichi who was hostile to Jack at first. Has a hatred of samurai as her family was killed by them. Eventually warms to Jack and starts showing affection for him, though he doesn't think of them being any more than mere friends.
• Momochi – adviser to Shonin. Mistrusts Jack until the end of the book.
• Tenzen – son of Shonin and an expert with shuriken. Strikes up a quick friendship with Jack. Gives Jack a gift of five shuriken.
• Shonin – head of the Ninja Village.
• Shiro – a ninja who constantly moans about anything. Betrayed Jack and the rest of his clan to daimyō Akechi and was killed by Gemnan.
• Akechi – Daimyō of the province. Dislikes Ninja to the core. Killed at the end of The Ring of Earth.
• Ishibe – Tenzen's uncle. Beheaded by Samurai in the assault on the Ninja Village.
• Zenjubo – one of the skilled Ninja in the village.
• Kajiya – a blacksmith for the Ninja, forges many of their weapons.
• Gemnan – cruel Samurai who is daimyō Akechi's right-hand man. Was responsible for killing Miyuki's family. Delights in torture.
• Date Akiko – older sister of Hanzo/Kiyoshi, Jack's samurai best friend and former student at the Niten-Ichi-Ryu, was in the battle of Osaka Castle.

 Jugo - master of fighting with papuce

• Ronin – seemingly just another masterless samurai. However, his past was tragic. A spy disguised as a monk killed his father, Obata Torayasu, and Ronin failed to protect him. Hence he took to drinking sake to forget his guilt at being helpless. This incident also caused him to foster a hatred for monks, which drove him to join Botan's gang upon hearing of a spy (Jack) dressed as a monk in the vicinity after he desperately needed work. What he didn't expect was that Botan would backstab him by drugging his sake and wiping his memory of their plan to trap Jack for most of the book, he eventually becomes Jack's true friend.
• Hana – a highly skilled thief and also a hinin (outcast) that Ronin and Jack meet on their journey. At first, she was an unwilling captive of the two, but quickly proved her worth with her quick wits, especially when Daimyō Sanada tried to take their lives. Jack would eventually entrust her with his inro to warn Akiko that Kazuki was targeting her to kill as well. She was last seen departing for Toba, where Akiko and family reside. In the Ring of Fire, it was revealed that she got lost in the Iga mountains and chanced upon Shonin's ninja clan. After some explanation as to how she knew Jack, Hanzo was tasked to guide her to Toba. She is described to be young, most likely between the ages of ten and fourteen.
• Riddling Monk – a devious-looking character who was in possession of Jack's rutter. Has a huge following of disciples. He did encounter a drunk Ronin at some point and took the rutter away from him. Ronin failed to get back the book since he answered the Monk's riddle incorrectly. Jack and Hana would get the rutter back by answering his 3 riddles late in the book, which is in a ruined temple on a stormy mountaintop.
• Matagoro Araki – Headmaster at the Yagyu Ryu whoms't is in possession of Jack's daisho, and challenged him to a duel which Jack won.
• Botan – skilled and ruthless samurai, leader of the group that assaulted Jack and robbed him of his possessions. He hired Ronin as part of his plan but drugged his sake as well as a cover. Killed by Ronin after he tries to kill Jack and Hana.
• Sanada – Daimyō of Nara Province. Challenged Jack to a game of Go, or Japanese Chess. His flag is black and white checks, as is the rest of his palace and his clothes.

• Hayato – son of the late daimyō Yukimura and a highly proficient archer. Deceased.
• Yuudai – able-bodied and immensely strong samurai who wields a nodachi. Shows deep feelings for Neko.
• Miyuki – the young kunoichi (female ninja) from the earlier Ring of Earth and is one of Jack's group of defenders of Tamagshi village. She develops a friendship with Neko and admires her bravery.
• Saburo – Jack's friend from the Niten Ichi Ryu school of the first three books. On his Musha shugyō, Saburo shows up in the nearby market town due to a rumour about Jack being in the area, remaining to help defend Tamagashi village.
• Neko – an orphaned girl who is both deaf and mute. She cooks for Jack's squad and the farmers, and also learns some ninja skills from Miyuki. Shows deep affection for Yuudai.
• Junichi – head of the Tamagashi village Jack resides in. He has his mother living with him. Deceased.
• Yoshi – the elder of Tamagashi village.
• Toge – one of the village leaders, and highly distrusts Jack, doubting his abilities as a samurai. E
• Sora – one of the elderly farmers.
• Akuma – the main antagonist in the story. Nicknamed "Black Moon", He is an utterly heartless warrior who plunders the villagers' rice for his own every year at full moon, leaving them with almost nothing to eat. He is killed by those whom he ruthlessly oppressed in the end.
• Nakamura "Scarface" – Not to be confused with Sensei Nakamura, Nakamura is one of Akuma's most skilled henchmen, wielding an axe with fierce abandon. He tries to take down Jack with him knowing that he is dying, but fails and drowns.
• Sayomi – female bandit who serves Akuma. Wields a naginata. Her hair was ripped from her head with her scalp. Deceased.
• Kurochi – nicknamed "The Snake" he is highly proficient with using the musket to shoot targets from long range. Thanks to Neko's efforts, he dies in an explosion after falling from a watchtower.

• Tatsumaki – The Pirate Queen. Leader of the Wind Demons(a pirate organisation), and sees Jack as a valuable asset. Shows exceptional skill with the naginata. She is very ruthless and cruel.
• Saru – Tatsumaki's pet monkey. Shows apparent affection towards Jack, but she steals Akiko's Pearl from him and becomes extremely possessive of it.
• Skullface – part of Kurogumo's crew. He detests Jack, believing him to be the root of their misfortunes. Betrays Tatsumkaki along with Tiger and Snakehead, but all were killed in the end by "Dragon Eye".
• Tiger – part of Kurogumo's crew.
• Snakehead – part of Kurogumo's crew.
• Kurogumo – Captain of the Black Spider.
• Li Ling (Cheng) – hails from China, and soon becomes a member of the Wind Demons. Aspires to become a great pirate, like Tatsumaki. Drawing inspiration from Hua Mulan, she disguised herself as a boy as the Demons do not allow girls as crew. Assists Jack and friends on several occasions. She would go on to play a pivotal role in helping them escape from the lagoon.
• Arashi – Commander of Daimyō Mori's naval forces. Cruel by nature. A personal vendetta against pirates
• Wanizame – female Captain of the Great White. She and her crew were all killed during the final assault against the Nihon Maru.
• Kujira – Captain of the Killer Whale;'. Presumably killed in the final battle. His ship was then overtaken by Sea Samurai.
• Hebi – Captain of the Jade Serpent.
• "Dragon Eye" – apparently the infamous ninja back from the dead. However, that ruse was destroyed when Jack manages to unmask him in a duel – revealing him to be a kagemusha – or Shadow Warrior – serving as Dragon Eye's replacement.

• Benkei – an artful-dodger-type character who may or may not help Jack on his journey.
• Shiryu – a Shodo writer who helps Jack when Benkei is wounded and teaches Jack the reverse grip sword technique
• JunJun – a kabuki girl who is later Benkei's crush.
• Daimyō Kato – the daimyō of Kumamoto manages to capture Jack for 3 days until he escapes.
• Takumi – Catholic farmer saved by Jack
• Daimyō Matsukura – wants to kill out Christianity in his province
• Captain Hendrik Spillbergen – captain of a Dutch ship which took Jack, Yori and Akiko to England
• Masamoto Takeshi – samurai sword master, Jack's guardian, general in the battle of Osaka castle but banished by the shogun. Returns in the Ring of Sky as a messenger who then strips Kazuki of his samurai status.