SAKAMOTO DAYS — RPG

Gaku is a relaxed and laidback young man, talking calmly with Slur about the JAA and comparing their nervousness to a returning student going to school rather than a life-and-death situation. Besides his extremely casual behavior, Gaku is also cold and cruel towards his opponents and victims, casually killing JAA's members without hesitation or mercy and brutalizing the teenage JAA applicants, caring little for collateral damage. Besides his extremely casual behavior, Gaku was also be an extremely brutal person to deal with, killing JAA members many times without hesitation or mercy. He disregarded any pain or collateral damage done to Shinaya when he overexerted the man's body while controlling him and was shown to have fun during fights or even when killing a strong opponent, commenting that the action of killing is something you have to enjoy or it's a waste. Gaku is a tall and muscular young man with spiky slicked back bluish-gray hair and black eyes (hot pink in the manga) adorned with a red eyeliner in the outer corner. He wears a pair of black square-shaped earrings, a high-collared navy blue jacket with a yellow button that loosely falls around his body that is covered in multiple scars with the sleeves rolled up, bandaged hands, navy blue baggy pants and white sneakers with light grey stripes and a black lace (the sneakers are fully white in the manga). He always carries his weapon wrapped in bandanges over a bag in its right arm. After his fight with Takamura during the events of the JAA raid, Gaku lost his right ear, parts of his left middle and ring fingers, and his entire right hand. Later on, Kashima would reattach Gaku's fingers and hand but would not be able to reattach Gaku's ear. As he now wears a circular-shaped patch in the place of his missing ear. Gaku carried around a mace-like weapon with a pole and cubical head covered in spikes, vaguely resembling that of a meat tenderizer. The tip of the mace also shot laser beams. It was destroyed in his fight with Takamura but was later replaced. Gaku was seen playing multiple times with a PlayStation Portable he keeps by himself and utilizes even during fights or whenever he is bored.

Kei Uzuki, also known as "X" or "Slur" is the main antagonist. He is a serial killer seeking to overthrow the JAA with a group of fellow assassins. Roughly around the same time Taro Sakamoto was given his bounty, Uzuki slaughtered one-fourth of the assassin industry, leaving a large 'X' mark at the scene of his crimes written with the blood of his victims. Uzuki is a seemingly slim man of average height. He has medium-length white hair with a long fringe that often covers part of his emotionless blue, cat-like eyes, also covering even his nose when leaning forward. His hair also covers his ears and is styled in a messy, middle-part haircut. He usually wears a light grey turtleneck under a greyish-yellow coat that reaches below his knees, alongside black pants and formal black shoes. Kei Uzuki was initially portrayed as a calm and cold man, being able to kill a quarter of the assassins in cold blood without a hint of words. He is also a sadist, considering he almost lack any remorse for his killings and provoked Sakamoto by mentioning his 6-years old daughter when Sakamoto refused to fight with the intention of taking the former's life, hinting that he may harm Sakamoto's family if he were to be left alive. However, during his groups attack on the JAA, Uzuki showed a friendlier, more caring side which was seen through his conversation with Gaku and the remorse he felt at Uda's self-sacrifice for the others to escape Takamura. As he demonstrated multiple times, Uzuki's cold and deadly personality changes radically whenever he is alone with his friends or those he cares about, showing a softer and friendlier side of him which also seems more vulnerable. In the past, Uzuki was shown as a reserved, timid, and shy person who firmly believed that killing is wrong and did not kill assassins unless required by the mission or the specific target. His older brother Sei Asaki took advantage of it by threatening to kill Gaku and Uzuki's other friends in the orphanage where he was born if he failed to uphold his end of a deal. Asaki's threats might also have been the reason why Uzuki's main goal, after completing the mission to escort both the daughter and wifeof the JAA chairman to safety, was to return to the orphanage where he was raised and save all his friends. His accidental murder of Rion Akao led to him abandoning his morals and become the villain that he is today. Uzuki suffers from Dissociative Identity Disorder, a condition which developed as a way for Uzuki to deal with the trauma. This condition allows Uzuki to create multiple personas, changing his own characteristics to match those of a specific individual; these personas remain even after the person they're based on dies and are so accurate that even other people who were close to the person whom Uzuki is emulating have trouble telling the difference, an example of this would be Sakamoto and Nagumo who admitted that Uzuki's Rion persona resembled their old friend so closely that it's hard to distinguish between the real Rion and Rion-Uzuki. Since the death of Haruma, Gaku's unknown fate, and the seeming assimilation of the Takamura personality, Uzuki has become a jaded and uncaring individual, a shell of his former self. He seemingly no longer cares about his foster siblings, letting the Rion Akao personality influence his opinions on Tenkyu and is fixated on the goal of destroying the Japanese Association of Assassins no matter the cost. Uzuki can also mimic, if not outright replicate, the individual's mannerisms and capabilities as well. An example of this can be seen with his Takamura personality who not only mutters unintelligibly just as the real Takamura did but is also a master swordsman, being able to match and eventually cut down the real Takamura despite Uzuki having not shown any proficiency with wielding a katana up to that point in the series.

Toramaru is a young woman wearing a school uniform, which consists of a white shirt with a bow tie, a black sleeveless cardigan, a long black skirt, black socks, and a school bag. She has black hair with a fringe and two long white braids. Her eyes are a light purple, and her pupils are cross-shaped. Toramaru is an otaku who is a hardcore Taro Sakamoto fan before she found out his true identity in JCC Transfer Exams Arc, but she later became a fan of him again. Although she looks adorable and innocent, she can be cruel when being triggered and kill opponents without second thoughts.

Mafuyu is a teenager of average height and build. He has short dark blue hair with bangs that covers most of his face, sharp eyebrows, sunken black eyes and is constantly seen with a teal surgical mask to protect himself from germs, but he now uses a turquoise gas mask he ocasionally wears a teal gas mask. He wears a long-sleeved dark purple shirt kept with a black belt and his boots he uses as a weapon. Mafuyu is a very vocal germaphobe, going to extreme lengths to avoid dirty things and reacting with incredible disgust whenever he gets dirty. He won't even use his hands in battle due to not wanting them to get filthy, opting to use blades hidden inside his shoes to fight. Despite his quirks, Mafuyu can remain incredibly calm in the heat of battle and even when faced with death. He is also shown to be timid and appears to see other people like Shin as influences quite easily, despite insulting him with names like 'old man' at first.

Kashima is a tall man that wears a pink polo shirt under a magneta business suit, a burgundy floral-patterned tie, black belt with a silver fivel, brown shoes and the mask of a realistic reindeer head with a dark brown snout and cream-colored spots in the ears and under his eyes. Without his mask, he has sunken black eyes, sharp eyebrows, slicked back lilac hair with dark purple streaks and dark blue fingernails . He has an X-shaped stitch over his mouth that clearly showing his admiration for Slur. When Kashima was 17 years old, his hair was styled in a side fringe with short bangs covering the forehead and his outfit consists in a simple black t-shirt accompanied by pants and sneakers that are also black. Kashima is cordial, and business-oriented, and emphasizes a man who has polite manners when killing someone or something. He frequently meets his subordinates at casual venues such as karaoke clubs or fast-food joints and allows them to eat or drink on the job as long as it doesn't interfere with their work. He has a strong fascination with cutting-edge technology, expressing his disdain for standard guns and knives after becoming a cyborg. He seems to take great pride in his augmented body as shown by his disbelief when Taro Sakamotomanaged to beat him during their fight. Kashima's fascination with technology is so strong that he took over a research lab as an "independent project" to facilitate more research. However, despite his obsession with technology, Kashima is still a pragmatic and meticulous planner, rigging the laboratory to explode in case of an emergency as a form of scorched-earth strategy. Kashima has a twisted respect for life, such as when he started weeping for his subordinates when they were killed by Osaragi and Shishiba or how he violently stomped on a cockroach Mafuyu Seba had injured to give it a "merciful death" and has shown himself to be a very delusional and self-righteous person, following his warped ideal of justice and believing himself to be misunderstood as he's eliminating "bad people", despite said individuals only committing minor transgressions like bothering a cat when he was younger. Kashima also strangely dislikes Christmas and "people who talk back". He states that he has his own rules saying that he will not show someone his face until he trusts them and has his own moral compass, as shown when he disagreed with Slur's plan that involves endangering civilians, despite claiming that "revolutions require sacrifices" at another point.

Haruma was a tall young man with slicked back blond hair, the painting of a pink swirl on his face and sunken black eyes that are always seen closed. He wears a white wrinkled t-shirt, black pants, boots, a pair of golden-yellow triangle-shaped earrings, as well a brown waist that has four holders for his balls. Haruma was a relaxed and laidback man, calmly asking for a glass of mineral water when he walked into a diner, despite being surrounded by assassins, and was polite when asking for a JAAexecutive to come meet Slur. He also had a caring side, offering a stressed JAA executive a sports drink to calm down, and telling him to take deep breaths and to relax. He also made sure the executive wasn't harmed by taking away his gun so the others wouldn't immediately attack him. He encouraged Toramaru to keep up the good work and get better after she and Mafuyu sparred with Gaku, with the latter crying due to his loss. Haruma believed that if he just killed people normally, it would be unfair due to his immense skill compared to others, as he said to Shin. He also says he doesn't feel good about one-sided slaughter, hence why he uses the rules of sport so he can sort of match Shin's level in their fight. He called this "killing sportsmanship". self-controld self-control, commenting that despite being so angry that he wants to kill Shin, he won't in the name of his beliefs towards killing.

Kumanomi is a young woman of above-average height and medium build. She has green eyes with yellow pupils and lime green shoulder-length hair, which has been cut short when Osaragi threw her Buzzsaw at her in chapter 207. She wears a navy blue crop-top coat exposing her toned midriff, black harness, boots that go up to her thighs, and black gloves with metal plating on the back of the hand. She does not appear to wear a bra. She dons a pair of crescent moon-shaped earrings. During her fight with Hyo, she lost her right arm, that was eventually replaced with a dark grey prosthesis-like robotic arm that has an energy core in the center of the upper hand. Kumanomi is shown to be quite an intimidating and imposing woman as she scares both Gakuand Slur with just a glare. She is blunt, straightforward, impassive and holds manners in high regard, complimenting Mafuyu for showing his face and nearly killing Kashima for refusing. She herself is respectful, as she referred to Uda as "-san/Mr.". Kumanomi is described by Slur as having an extreme personality, seeing people as either a friend or an enemy, caring for her friends greatly and being merciless to her enemies. This was shown when she asked Hyo if he was the one that took Gaku's ear after taking his own ear and displayed a calm but intense rage about Uda's death. Kumanomi is also callous as she tormented Heisuke after hearing his ideals in refusing to take a life and not involving civilians in their fight.