Who is the Assassin Killer in Sakamoto Days? The identity of the X, explained

One of the major highlights of Sakamoto Days episode 5 was the introduction of a mysterious serial killer, who went on a killing spree, eliminating the professional assassins associated with the JAA (Japanese Assassin Association). Interestingly, the white-haired perpetrator left an X mark at the scene of his crimes, written with his victim's blood.

According to Nagumo in Sakamoto Days episode 5, the serial killing commenced at the same time Sakamoto received the bounty on his head. Therefore, JAA sent its elite team, The Order, to hunt down the perpetrator. Notably, the episode teased the appearance of the mysterious "X," whom Nagumo called the Slur.

So, who is the X/Slur in Sakamoto Days episode 5? According to Yuto Suzuki's manga, the mysterious "X" is Kei Uzuki, also known as the leader of the X Organization, a group of rogue assassins who want to overthrow the JAA. However, Uzuki's desire stems from his multifaceted personality, since he used to be a benevolent person in the past.

Disclaimer: This article contains major spoilers from Sakamoto Days manga.

Exploring Kei Uzuki's motivations as the Assassin Killer X in Sakamoto Days

Kei Uzuki in Sakamoto Days episode 5 (Image via TMS Entertainment)

The latest episode of Sakamoto Days anime teased the appearance of Kei Uzuki, the leader of the X organization, i.e., the main antagonist group in the series. With Uzuki at the helm, the X is comprised of rogue assassins who want to destroy the current order of the JAA with their twisted sense of justice. That's why, Uzuki always leaves an X mark with the blood of his victims at the site of his crimes.

So, who is Kei Uzuki, and why does he harbor such animosity toward the JAA? To understand his motives, one must take a detour and learn about Uzuki's past. According to Yuto Suzuki's Sakamoto Days manga, Kei Uzuki was raised in the Al-Kamar orphanage, along with Gaku, Kumanomi, and a few others from his current X organization.

Although the orphanage wore the garb of being a center for the refugees, in reality, it served as the training ground to prepare young children to become potential Order members for the future. The intense training at the orphanage endowed children with exceptional physical prowess, at the cost of freedom.

Kei Uzuki, as seen in the manga (Image via Shueisha)

Back then, Kei Uzuki was a reserved and shy person, who didn't want to kill anyone unless his missions compelled him to. Interestingly, Uzuki's older brother, Sei Asaki, exploited his benevolent personality and made him cooperate on reasonable grounds.

For example, during a mission to escort the JAA chairman's wife and daughter, Asaki asked Uzuki to kidnap them as bait to lure out the chairman. If Uzuki refused, Asaki threatened to kill Gaku and his other friends at the Al-Kamar orphanage. Undoubtedly, it was one of the major reasons behind Uzuki developing his X persona.

However, it was only the tip of the iceberg for Kei turning into a villainous figure. During his expulsion mission against Kindaka and the mission to escort the chairman's daughter and wife, Kei Uzuki formed a companionship with Rion Akao, whom he told about his plan to take a break from the JCC and return to the orphanage.

The duo realized their hearts were in the same place. Hence, after the mission, they went off the grid for more than a year. During that period of time, Uzuki and Rion became close, and the latter shared essential pieces of information on Nagumo, Sakamoto, and others. However, their going off the grid was a direct breach of the JAA's code in Sakamoto Days.

Meanwhile, Rion continued to do freelance assassinations because she knew that they needed money if Uzuki wanted to attack the orphanage and save his friends. Then one day, Kei Uzuki's brother, Sei Asaki appeared at their hideout with a final mission. He wanted Uzuki to kill a major threat.

However, the narrative for Sakamoto Days revealed that Uzuki's target was none other than Rion Akao. Asaki's twisted plan made Uzuki claim the life of the person he trusted. Later, Asaki taunted Uzuki by saying that he couldn't escape the assassin's world.

Sei Asaki in chapter 115 (Image via Shueisha)

Kei Uzuki had no time to mourn Rion's death since Taro Sakamoto arrived at the scene to carry out the punishment imposed by the JAA. Uzuki requested Sakamoto not to shoot him dead as he wanted to watch the sky while dying. However, Uzuki had a Situs Inversus, a condition where the vital organs are inversed on a person's body.

That's how he survived Taro Sakamoto's bullet in Sakamoto Days. As he crawled toward the society, he witnessed how the bystanders only watched him bleeding and refused to help. Suddenly, Kei Uzuki had an epiphany; he realized no one truly reached out to him aside from Rion.

Hence, he wondered why Rion had to die while the likes of Sei Asaki, the bystanders, and the other personnel at JAA, were still alive. Thus, after recovering from his wounds, Kei Uzuki's first agenda was to return to Al-Kamar orphanage. He killed 34 people and rescued his friends, including Gaku.

Uzui vs. Sakamoto in the manga (Image via Shueisha)

He set off on the path to destroy the JAA and everything associated with the organization, with his own X organization. He formed the group with his friends from the Al-Kamar orphanage and later recruited Kashima, Club Jam, Carolina Reaper, and other assassins.

Kei Uzuki's X/Slur persona was born from his deep hatred for the organization that drove him to kill the only person who cared him for. As a result, Kei developed a Dissociative Personality Disorder (DID), shortly after Rion's death. While he still had a benevolent self hidden in him, his X/Slur persona turned him into an absolute monster in Sakamoto Days.

Conclusion

Kei Uzuki's goals and aspirations in the Sakamoto Days series stem from his dark past, etched with bloodshed and betrayal. He was a kind man, who was turned into a villain by the organization that raised him and by the society that could only watch him from afar, refusing to lend a hand. It wasn't only Sei Asaki, but the organization as a collective entity that ruined his life.

Unfortunately, the only person who did care about him died at his own hands. That's why, Uzuki no longer cared what happened to the world. His persona vendetta gained priority as he sought revenge against those who wronged him.