|
 |
This Article Contains Spoilers -
WARNING: This article contains major spoilers. If you do not wish to know vital information on plot / character elements in a story, you may not wish to read beyond this warning: We hold no responsibility for any negative effects these facts may have on your enjoyment of said media should you continue. That is all. |
  |
This article's content is marked as Mature The page contains mature content that may include coarse language, sexual references, strong drug use, extremely traumatic themes, and/or graphic violent images which may be disturbing to some. Mature pages are recommended for those who are 18 years of age and older. If you are 18 years or older or are comfortable with graphic material, you are free to view this page. Otherwise, you should close this page and view another page. |
| “ | Awesome. | „ |
| ~ Gaku's signature phrase |
Gaku is is a major antagonist in the comedy-action manga series Sakamoto Days and its 2025 anime adaptation. He is an assassin working with Kei Uzuki and a central member of Slur's Group to overthrow the JAA.
He is voiced by Kōki Uchiyama in Japanese (who also voiced Meruem in Hunter x Hunter and Tomura Shigaraki in My Hero Academia) and Jacob Bertrand in English.
Personality[]
Gaku is a relaxed and laidback person, 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, as well showing to be very protective towards Kashima.
Besides his extremely casual behavior, Gaku is also cold and sadistic towards his victims, casually killing JAA's members during its introduction without mercy and brutalizing random people by controlling Shinaya just because he "hates teachers".
Biography[]
Past[]
Gaku, along with others like Kei Uzuki and Kumanomi, was raised in the Al-Kamar Orphanage — a facility secretly operated by the JAA to train orphans into assassins, with the ultimate goal of grooming them to become members of The Order. The orphanage was run by Sei Asaki. When Gaku was 13, Asaki regularly abused him and even used him as leverage to force Uzuki into carrying out killings or following commands he resisted. Eventually, Uzuki broke into the orphanage, killed the managers while guarding it,freeing the orphansi in the process. Afterwards, Gaku went on to join X's Organization alongside other former orphans like Haruma.
Death Row Prisoners Arc[]
Gaku makes his debut during an assault on the JAA headquarters, launched alongside Uzuki. This attack follows the release of several Death Row prisoners by Uzuki as a diversion to keep the JAA occupied. Approaching through the front entrance, Gaku kills two security guards who question them.
Following Uzuki’s orders, Gaku storms the building, slaughtering every JAA staff member he encounters—claiming around forty lives within just two minutes. When he opens a door, he’s met by a firing squad led by Takebe, but emerges unscathed and wipes them out with his mace. Just as he’s about to kill Takebe, Inoda crashes through a wall and punches Gaku through another. Gaku retaliates by shooting Inoda in the face with a gun built into his mace and then smashes him out of the building, through a neighboring parking structure, and into a van.
As Gaku ascends the building, he senses a threatening presence in a dark corridor—Takamura. Realizing the danger, Gaku attempts a swift overhead blow with his mace, but Takamura blocks it. In the clash that follows, Gaku loses two fingers and an ear, unable to fully withstand Takamura’s attacks. When he swings again, Takamura shatters his weapon. Gaku flees and reunites with Uzuki, Sakamoto, Uda, Shin, and Apart.
Takamura catches up and strikes Uda, who had tried to ambush him. Gaku uses the distraction to attack with what’s left of his mace, but Takamura cuts off his arm. Gaku kicks the severed limb at Takamura, temporarily knocking him back. Just as he’s about to go in again, Uzuki pulls him away, saving him from another devastating strike. Gaku uses the chaos from Uda’s suicide bombing to escape with Uzuki.
JCC Transfer Exams Arc[]
After escaping with Uzuki following their encounter with Takamura, Gaku is later seen in the hideout with Kashima, reattaching his severed arm and ears. He replaces one of his ears with a dark, earring-like device, while Kashima successfully reattaches his arm. Thanks to Takamura’s precise slicing, the cut was clean enough to keep the muscle tissue intact, making it possible for Kashima to sew it back on. Once his arm is fixed, Gaku and Uzuki discuss their next move. Gaku first inquires about Takamura, and Uzuki explains they need to recruit new members due to Uda’s death, who gave his life to ensure their escape.
Later, during the JCC entrance exam, Shinaya suddenly launches an attack on Toramaru. It’s revealed that Gaku is controlling Shinaya remotely and is using him to attack the applicants to evaluate their combat potential for recruitment into X's Organization. After landing a devastating blow on Toramaru, the other applicants begin to notice Shinaya’s strange behavior, eventually realizing it's Gaku pulling the strings. While the chaos unfolds, Gaku casually snacks and drinks, prompting Kashima to scold him for being careless during the operation.
Continuing to manipulate Shinaya, Gaku has him attack both the applicants and the examiner. During a clash with Shin, Toramaru, and Kaji, Shinaya suddenly crouches in confusion—only for it to be revealed that Gaku accidentally slammed his head into a wall while wearing the visor, once again drawing Kashima’s frustration. Despite effortlessly overpowering the applicants through Shinaya, Gaku is eventually stopped when Sakamoto intervenes, defeats Shinaya, and forces Gaku to deactivate the device.
JCC Infiltration Arc[]
Gaku is first seen sleeping on the floor of X’s factory hideout, completely unfazed even when Toramaru trips and falls directly on him or when Kashima detonates a bomb nearby. His total indifference to chaos highlights his unpredictable and dangerous nature. He later offers to destroy the JCC himself, but Kashima turns down the offer, citing the difficulty of breaking through the surrounding environment and ongoing strategy.
Although Gaku doesn’t participate directly in the initial stages of the JCC infiltration, he is present during strategic discussions and is updated by Uzuki about the return of Haruma and Kumanomi, signaling preparations for the next phase of the organization’s plan to eliminate the Order.
Throughout the arc, Gaku plays a more passive role but serves as an ever-present, looming threat due to his extreme power, violence, and instability. His moments of inactivity and silence contrast sharply with his known reputation, reinforcing the tension that he could erupt into action at any moment.
Bangkok Arc[]
Gaku is seen spending downtime with Mafuyu Seba, casually playing football. This peaceful moment is abruptly disrupted when Kumanomi and Haruma arrive, with Kumanomi kicking the ball so hard it slams Gaku against a wall. The encounter immediately reestablishes Gaku’s vulnerability among his peers while introducing the volatile personalities of Uzuki’s allies.
Soon after, Uzuki formally introduces Haruma and Kumanomi to the rest of his team, revealing that all three—along with Gaku—grew up together at the Al-Kamar orphanage. This shared past solidifies Gaku’s long-standing connection to Uzuki’s inner circle and hints at deep, possibly complicated loyalties between them. Kumanomi and Haruma also mention that Gozu and Tenkyu will join them later, further fleshing out the group’s Al-Kamar origins.
A significant detail about Gaku comes to light through Kumanomi’s later confrontation with Hyo: Gaku’s ear was torn off in the past, an injury she believes Hyo caused. This motivates her aggressive attacks on Hyo, even though Hyo himself doesn’t recognize Gaku. The incident positions Gaku as a victim of past violence that still fuels ongoing grudges within Uzuki’s network.
While Gaku does not take a direct combat role during the events in Bangkok, his presence is pivotal in revealing the personal histories and tensions among the assassins. His injury becomes a catalyst for conflict, and his roots in Al-Kamar place him firmly within the web of relationships driving much of the arc’s interpersonal drama.
Assassination Exhibition of the Century Arc[]
Gaku enters the Assassin of the Century Exhibition alongside Kumanomi, Carolina Reaper, and Haruma, then splits from the group to locate the JAA Chairman. He encounters Nagumo and is disappointed that he won’t get to fight Takamura. Despite agreeing to leave each other alone since they aren’t each other’s targets, both betray the truce and engage in combat. Gaku strikes Nagumo, sending him flying into a wall, but Nagumo remains unharmed. Gaku ignores Nagumo’s question about who is stronger before the fight resumes.
As the battle moves through the exhibition, Gaku assesses his power relative to Nagumo, who notes that Gaku is likely the best opponent he’s faced. Gaku, calling killing a game to be enjoyed, continues his attacks despite being injured. Nagumo uses various weapons to counter him, including stabbing Gaku in the forearm and abdomen. Gaku responds with powerful attacks using a mace and a mac cannon, even tossing a car off a ledge. Both fighters sustain injuries, and Gaku is eventually revealed as the severely wounded figure when a body initially thought to be Nagumo’s is examined, while he continues to fight. Gaku is stoppted by Takamura who kills the young man by impaling his back with his katana.
Powers and Abilities[]
- Superhuman Strength: Gaku obliterated half of a JAA guard's torso with a casual backhand strike and later on proceeds to literally tear apart multiple assassins with his mace. When controlling Shinaya, Gaku was nigh-unstoppable, wiping out almost every JCC faculty on the island, overwhelming Shin Asakura and Joichiro Kaji as well as manhandling powerful applicants such as Mafuyu Seba and Nao Toramaru until he was finally stopped by Taro Sakamoto's arrival.
- Superhuman Speed: Gaku is fast enough that several skilled assassins, were unable to defend themselves from his attacks. He also managed to somewhat avoid Takamura's extremely fast Iai attacks, turning otherwise-lethal blows into moderate injuries. When controlling Shinaya, Gaku was able to quickly respond to Sakamoto's attacks.
- Superhuman Durability: Gaku is capable of taking multiple strikes that would kill any normal human and remained completely unfazed. Even after losing his right hand and two of his fingers, Gaku barely flinched.
Fighting Style[]
- Mace Wielding: Gaku carries around a large mace with a long pole and cubical head covered in spikes, vaguely resembling that of a meat tenderizer. The tip of the mace also contains a powerful laser cannon. It was destroyed in his fight with Takamura but was later rebuilt or replaced.
- Expert Combatant: Gaku has defeated numerous skilled opponents, including Shin Asakura and Joichiro Kaji, and has overwhelmed multiple JAA members while controlling Shinaya, as well during his quarrel against Nagumo in the museum.
Trivia[]
- Gaku was around 13-years old when he escaped from Al-Kamar, making him the youngest member of the Slur's Group.
- Gaku is shown to be a big fan of the Resident Evil series, at the point of even mentioning the games when controlling Shinaya in the manga.
External Links[]
- Gaku on the Sakamoto Days Wiki
[]
 Villains
| ||
|
Slur's Group Japanese Association of Assassins Death Row Killers Danshokai Other Assasins Ando's Group Others | ||