Hachimaru is an adolescent boy with messy light-brown hair and had a frail physique. He wears a pair of half-rim glasses and has a small tomoe-shaped marking on his forehead. He typically dresses in an asymmetrical beige hooded jacket with a long right sleeve and a short left sleeve, over a dark blue shirt and matching harem pants.
Initially, Hachimaru spends much of his time tethered to a life support device in his house by several large tubes and wires plugged into the back of his head, and his left arm and leg are replaced by simple, doll-like prosthetics. He often wears a VR headset, which he uses to play online games. Later after becoming a samurai, his missing limbs are replaced with less obvious cybernetics and he dons a white belt with pouches and scabbards for his swords, bracers on his forearms and calves, and slip-on shoes.
After traveling into space with Daruma, Hachimaru switches his outfit to a black hooded jacket and matching pants. He also ties his hair back into a spiky ponytail and switches his glasses out for a pair of black goggles. While his goggles are normally positioned on the back of his head below his ponytail, during the battle he wills them onto the front of his face to cover his eyes.
Hachimaru began as a rambunctious brat, constantly complaining about his life and arguing with his dad every chance he gets. He also loves to play video games and is even the number one player in a popular fighting game. More than anything, Hachimaru wanted to go outside and meet new people, but his weak body prevented him from doing that. He is a kind and compassionate person, willing to help and defend others if they truly need it.
After becoming a samurai, he shows that he is sympathetic to those whose lives are similar to his, and will go out of his way to help them. Underneath his tough-guy act, Hachimaru is quite insecure about himself, believing himself to be a weakling even after becoming a samurai. This insecurity drives him to lie about his past out of fear that people will think less of him. However, he discovers his inner bravery and learns that others can accept him regardless of his past, and he finds a new reason to be brave: to protect that which is precious to him despite his weakness.
As a child, Hachimaru aspired to be a samurai as famed as Fudo Myo-o. However, his sheltered lifestyle made him unable to understand the gravity of life as a samurai. Initially, he took his training under Daruma lightly. He would become easily distracted from his master's teachings due to his dislike of long speeches. He was also very impatient and haughty, shown by his attempts to use moves above his skill level without any training and expecting to succeed on the first try. He also had trouble admitting his inexperience when he failed. Despite these traits, he still pushes forward with his training until he improves.
Hachimaru's encounter with Ata exposed him to true hardship, forcing him to openly acknowledge his weaknesses. The experience made him accept his flaws and strive to become a better samurai for the right reasons. As such, he becomes more patient, humble, and willing to listen to others. He begins showing more patience and respect, enduring his master's lectures without complaint and dropping his trait of interrupting others while they are speaking, and improving his social etiquette.
In battle, Hachimaru's more astute side shows. Because of his lack of blade work training, he compensates for his bad swordsmanship using his instincts as a professional gamer. He quickly studies a foe's movements and weapons to strategize, predict an opponent's move, and locate openings to exploit. However, he also has a one-track mind in battle, often focusing too much on the enemy in front of him and missing details in his surroundings.
Hachimaru's life began when the dangerous samurai of the Ususama Style sought to unlock the power of two artifacts left behind by Fudo Myo-o: Pandora's Box and Mandala's Box. The boxes can only be opened by seven specific Samurai Keys. However, the incalculable number of Samurai in the universe on top of the Samurai yet to be formed from dormant Locker Balls meant finding the right Keys could take lifetimes. Impatient, the Ususama decided to make artificial samurai with Keys that could open the boxes. However, the "Spare Key Project" was only a partial success: while only seven beings were supposed to be created, eight were spawned. The eighth baby disrupted the balance of power among the created siblings, making the entire group unable to serve their purpose.
Because the eighth child was an accident, it had several deficiencies and was born weak and dying. The baby boy, named Hachikaku by his creators, nonetheless clung to life. However, a scientist working for the Ususama realized the horror his masters would unleash if they opened the legendary boxes, and decided to kill Hachikaku to disable the project permanently. The scientist, Dr. Furuta, went to kill baby Hachikaku, but he could not bring himself to do it. His heart was moved by the baby's fighting spirit, so he instead took the child and fled to a planet far away from his former masters. Settling down there, he raised the child, renamed Hachimaru, as his own, determined to keep him safe and hidden from the Ususama.
Hachimaru was too weak to live on his own, so Furuta used his expertise to build a life support device that kept his son alive, but restricted his movements. Hachimaru also had to undergo regular medical procedures and was unable to eat actual food due to his conditions. Though hampered by these things, he nonetheless desired to become a legendary samurai and explore the galaxy, even wishing for it to be so on shooting stars. He also developed a video gaming habit and flourished at it thanks to all his free time, eventually becoming his planet's number one player of a popular fighting game. Though he loved his father, he was constantly frustrated by his restricted movement, especially since his dad kept promising to complete a device he could use to move around while never actually finishing it.
Abilities and Powers
- Samurai Gravity: Due to being a samurai, Hachimaru has a limited degree of control over the molecules that form matter and the gravity H-Particles emit. When applied, he can reshape matter and gravity at will. This allows for the use of generic samurai abilities.
- Healing Factor: Hachimaru's cyborg body can repair itself from any injury. Anything from loss of limb to being stabbed in the head will heal given enough time. According to Ryu, Hachimaru's healing speed is above average. As with all samurai, Hachimaru's healing will fail if his will to win ever wavers in battle, allowing him to die.
- Holder Control: Hachimaru can reshape the body of his Key Holder into various forms, such as a flying machine and armor.
- Gravitational Pull: While all samurai have gravity that draws other samurai to them, it's noted by Daruma that Hachimaru has an unusually strong gravity about him. This causes other keys - and the samurai who own them - to be drawn to him, and in turn, allows him to track samurai keys. However, since he is not a full-fledged samurai, he cannot properly track other keys yet. His gravity can also be perceived by enemies, allowing them to locate him as well.
Hachimaru Key can display a map showing the other Samurai Key's Box.
- Key License
- Kongo-Yasha Style (downloaded from Daruma)
- Takatsuna' Samurai Soul: Before becomes a samurai, Hachimaru was kept alive by this samurai soul working in place of his heart.
- After becomes a samurai, Hachimaru earned his samurai soul.
Hachimaru has an active Trinity.
- Key Holder
- Ann - Ann can use her powers as a Princess to enhance Hachimaru's fighting abilities. By praying, she can increase his speed, strength, and the power of his Samurai Soul. The current strength of his bond with Ann allows her best prayers to multiply his abilities, including his numerical statistics, by a maximum of eight.
- Samurai Soul Blade: A samurai soul can be fused with a Handle Bone from a Holder turning into an energy blade stronger than any metal blade.
- Hachimaru's Samurai Soul Blade: Using the handle bone stored in his right arm and his samurai soul. While he initially could not form a proper blade, training allows Hachimaru to form a true Samurai Soul sword. When his Princess delivers a strong enough prayer, Hachimaru's Soul can change into a shining white sword more powerful than even a seasoned Samurai's Soul.
- Katana: Hachimaru carries an antique blade from his father's collection as a secondary weapon.
- Hidden Blade: Upon becoming a Samurai, Hachimaru's artificial left arm was integrated into his cyborg body. The retractable cane stored inside that arm was upgraded with a blade attached to the end. Now serving as a hidden sword inside his forearm, he can release it with a thrust at will, making it useful for surprise attacks.
- Professional Gamer: Due to being unable to leave his house, Hachimaru plays many video games. His proficiency is great enough that he became his planet's best player in a popular samurai fighting game created by Daruma
- Battle Instincts: Thanks to his experience with gaming, Hachimaru has developed an exceptional talent for quickly analyzing and anticipating the moves of his opponents. These instincts allow him to conquer stronger and more experienced Samurai despite his lack of real-life fighting experience. His instincts are impressive enough that even his master considers them on par with elite Samurai.
- Katana Skills: Though untrained, Hachimaru is skilled enough in blade work to fend off a trained ronin with little help. His experience as a gamer also allows him to apply moves and tactics used in his video games to fight in real life. His samurai body also increases his cutting abilities, to the point where he could cut a tank in half with a single slice.
- Pilot Skills: Hachimaru can pilot his Key Holder, Hayataro fairly well. Even without training, he can fly it with ease.
- Kongo-Yasha Style
Hachimaru's relationship with Furuta was positive, albeit a little strained on his end. Hachimaru was often annoyed by his father's helicopter parenting and sometimes got into arguments with him over it. This was exacerbated by his father's promises to help him experience the outside world, only to put it off repeatedly. Under the surface, Hachimaru loved Furuta greatly. He cares about him, takes his instruction to heart, and worries about his father's safety more than his own: he has a strong wish to protect him, to the point where he would die for him. Furuta's death grieved Hachimaru a great deal, but it also inspired him to work towards becoming a true Samurai.
- Hachi (
八?) means "Eight", Maru ( 丸?) means "Circle" but is a suffix for names of people too and Kaku ( 角?) means "Horn".
- Hachimaru's name contains the kanji for the number "eight", as Hachimaru is the eighth person Daruma met in person who wanted to become a samurai.
- Along with the lore of Samurai Eight: Hachimaruden, the number eight is connected to there being seven keys to open Pandora's Box and Hachimaru being the eighth key.
- There are eight codes a samurai must live by known as the Bushido Code.
- Number 8 is also considered a lucky number in Japan.