The Bomber (爆弾魔, Bomā—base kanji lit. "Bomb Devil/Demon") is a trio, composed of Genthru, Bara, and Sub, whose goal is to complete Greed Island. They do not hesitate to kill or to blackmail other players to get their cards.
Genthru appears to be the leader of the trio, acting as its spokesman and occasionally directing Sub and Bara. He was also described as the "main guy" by the latter, who referred to Sub and himself as his "wingmen", although it is possible that he was referring to the mechanics of Countdown rather than the hierarchy of the trio. Despite Genthru's possible authority over the other two members of the group, all three appear to enjoy equal standing in it, with most courses of action being decided through general consensus rather than unilateral decisions.
Despite the motivation of the Bomber(s) being mercenary and their methods ruthless, the relationship between its members is closer than that of a simple alliance, as each member has expressed concern for the others' well-being. In fact, the firm belief that they ought to share all risks equally led Genthru to roll a Risky Dice for no reason other than Sub and Bara would be required to do so as part of a plan.
Genthru as well as Bara and presumably Sub were hired by Battera to finish the game Greed Island and claim the reward offered by the billionaire. While it is unknown when the three decided to join forces, Genthru was already planning to betray Nickes's alliance when he contributed to founding it five years prior to revealing his identity, although it was speculated that he might have been concocting the scheme for an even longer amount of time. The ability to remotely detonate the bombs placed by Genthru when the trio performs a specific action might suggest that Genthru, Bara and Sub had already formed an alliance before being hired.
Five years prior to the completion of the game, Genthru created an alliance with Nickes, Jispa and seven other players hired by Battera, passing himself off as another Nen user too weak to stand a chance at clearing the game. It is unconfirmed whether he was already a member of the Bomber at the time, or what Sub's and Bara's tasks were. Over the course of five years, the trio waited for the players of Nickes' alliance to collect enough cards while placing bombs on all the members, as well as a number of other players. In addition, Genthru began killing off other players and putting the blame on a violent murderer called "The Bomber" to be able to use the word casually in a conversation, so as to plant the bombs in his victims without their awareness. Meanwhile, he cultivated an image of The Bomber as a solitary, radical player who kills others just to cull the competition.
Greed Island arc
When the latest batch of players hired by Battera makes its way to Greed Island, Genthru approaches Jeet and activates Countdown on him, killing him in Antokiba a mere few hours after his ingress. Genthru subsequently joins other founding members of a players' alliance in their attempt to enlist the newest players, sharing with them information about the ruthless killer known as "The Bomber". Genthru keeps up the pretense for a couple more months, during which he plants bombs on the newest members.
When Nickes holds a conference in their secret base cave to announce that the alliance has managed to collect 90 different specified slot cards, Genthru makes his own declaration, revealing that he is, in fact, the Bomber and has attached bombs on all of the alliance members. After this shocking revelation Jispa tries to subdue the Genthru but has his face blown off by his Nen ability, Little Flower. The Bomber then resumes the explanation of his abilities, as well as of how to deactivate Countdown. Disclosing this information starts the countdown on all the bombs attached to the alliance members. Genthru offers to disarm them in return for all of their specified slot cards. He announces that he will wait at Battera's castle and escapes the base with "Leave". He waits by the JoyStation Consoles with Sub and Bara until Puhat arrives. Genthru demands he hand over the cards, but Puhat reveals that he has come to propose himself as a mediator. Genthru kills him. Bara enters the game and shows Puhat's severed head at the alliance members gathered before the Shiso Tree, before demanding a "Leave" card and explaining that for the bombs to be deactivated, all three members of the Bomber must perform a ritual together. One of the founding members complies and is punched by Bara for not having obeyed sooner. Bara orders the group to assemble three more "Leave" before exiting the game.
A short while later Nickes meets with the trio in Battera's castle, handing them the ring in which all cards are stored. The announcement of Jispa's death leaves Genthru unaffected. Nickes insists that he remove the bombs, but Genthru replies that he must check if all the cards are in the binder and hands the ring over to Sub. The Bomber(s) and Nickes reenter. After verifying that all of the cards are in the binder, the three Bomber(s) press their thumbs together and uttering the command, detonating all of the bombs placed on the alliance members instead of dispelling them. Posthumorously Genthru declares that they never had any intention of letting them live. The incident nearly kills all of the members of the alliance minus Abengane and Cuzco. As a result of the massacre, several cards previously hoarded by the alliance group are put back into the game's circulation.
Genthru, Bara and Sub continue to amass restricted slot cards and successfully establish a monopoly of "Angel's Breath" and "Night Jade", the former through "Clone". They refuse Tsezguerra's offer to trade several times due to his progress in the game. One day, they are contacted by the Single-Star Hunter who offers them three cards—"Patch of Forest", "Spirited Away Hollow", and "Miniature Dragon"—in return for "Night Jade" alone. The trio talks it over. Genthru believes the deal not to be a trap, but rather a byproduct of Tsezguerra's confidence in obtaining the cards he is missing before them. To collect the elusive "Wild Luck Alexandrite", they capture two players and force one of them to roll a Risky Dice and use "Lottery". However, their attempts fail and Genthru suggests going back to Masadora to restock. He is not concerned with the number of cards gathered by Gon's team and estimates that they will get stuck at around 65, claiming the groups they have to watch out for are Tsezguerra's, Tokharone's, Hagakushi's, the Bellam brothers, and the uncommonly belligerent Phinks and Feitan. At Bara's suggestion, the Bomber(s) devise a plan to steal rare cards from Tsezguerra using a combination of Risky Dice and Tax Collector's Gauntlet despite the associated danger. Seeing their determination, Genthru rolls the die himself, reasserting that they share all risks equally. This perturbs Sub and Bara, but Genthru comments that, at only 5%, the risk of backfire is negligible. The Bomber(s) are in congruence on the plan and when Tsezguerra contacts them again they accept his offer.
The Bomber(s) alter the faces of their two captives to make them look like Sub and Bara. They precede Tsezguerra and his team of Barry, Rodriot, and Kess at the site of the appointment. The two captives stand next to Genthru while Sub and Bara, each wearing a Tax Collector's Gauntlet hide nearby and surreptitiously watch the trade progress. The trade goes off without a hitch, but Genthru attracts the attention of Tsezguerra's team saying the trade was unfair. He then holds up two cards stating one is worthless, the other "Angel's Breath", and tells them to pick one. Behind them, Sub and Bara roll their Risky Dice and steal a total of eight cards from Tsezguerra's team. The Bomber(s) then return to Masadora and celebrate the success of their plan. Genthru then lists "Mad Scientist's Plastic Surgery", "X-Ray Goggles", and "Tree of Plenty" as cards that they should retrieve before going after "Plot of Beach" and stealing "Wild Luck Alexandrite" from someone else. He confidently declares they may as well begin to decide which three cards they should take to the real world. His name is mentioned in Gon's binder.
After Gon's team goes after "Plot of Beach" the first time, the Bomber(s) kill all their allies. When they manage to defeat Razor and his pirates and win the card, Genthru contacts Tsezguerra while spying on him and team, and demands they hand over the card they won in exchange for their lives. Genthru orders Tsezguerra to come alone to the gate of Masadora in one hour, lest they take it as a declaration of war. He also reveals that he killed the remaining people of Kazsule's Alliance, sparking Gon's wrath, who then challenges him. Genthru replies he will steal "Wild Luck Alexandrite" from him after dealing with Tsezguerra. After the conversation, Genthru rejects Bara's suggestion to steal a copy of "Plot of Beach" from Gon's team as he assumes that Tsezguerra would have the original, and checking a cloned copy of it with a Paladin's Necklace would cause it to be reverted. He claims that Gon's team will cave once Tsezguerra surrenders and insists on the importance of not letting the Single-Star Hunter recover.
An hour passes and Tsezguerra with his team confront the Bomber(s). In an act of a declaration of war, they steal cards from the Bomber(s) and use an "Accompany" to return to Masadora. The Bomber(s) check their binders and notice no important cards were taken. Noticing Tsezguerra's unusual fighting spirit, Genthru comments it will be tough to beat him. That night Kess shoots a dart at Sub, but Bara intercepts it. Genthru tells his partner to not bother trying to go after this Kess uses an "Accompany" to fall back to Masadora. He deduces that Tsezguerra's team is tracking them through a Nen ability and decides to resort to more drastic measures. The Bomber(s) begin to attack players coming out of Masadora's Spell Card Shop while looking for the person supplying Tsezguerra's team with spell cards, forcing those who have never met Tsezguerra to buy cards for them and killing the ones who have. Once they have gathered enough spell cards to give chase to Tsezguerra's team, the Bomber(s) go after them. The chase begins and Team Tsezguerra leads the Bomber through a spell card-fueled chase throughout Greed Island. Once Team Tsezguerra's spell cards start to dwindle, Genthru remains with impostors while Sub and Bara stake out the Spell Card Shop. When Tsezguerra's team leaves the game, Genthru and Bara follow them and kill Sabazushi.
Unable to track down Tsezguerra and fearing the loss of their data, the Bomber(s) eventually go back into the game and wait for the Hunter in front of the Shiso Tree. When they stay out of the game long enough that their data is canceled, Genthru decides not to worry about Battera canceling the reward and plans to steal Gon's team's cards. After checking their spells, Genthru decides to fight Gon if it comes down to force, assigning Biscuit to Bara and Killua to Sub. The Bomber(s) use an "Accompany" to fly to Gon's team's location and pretend to have made a deal with Tsezguerra, offering to make one with them as well. Killua points out that they have no evidence of a deal, which causes Genthru to threaten to kill them if they don't hand over their cards. The Bomber(s) chase them until they seemingly run out of spells in Masadora. Unable to find them, the Bomber(s) first check the spell shop and then track them down via "Accompany". Confronted, Gon's team splits up. The members of the two groups engage in one-on-one battles as previously prescribed by Genthru.
Gon counters Genthru's first offensive, causing the Bomber to deduce that Gon is aware of his abilities. Gon then proposes wager where the one to admit defeat, surrenders his cards to the winner. Genthru refuses at first but accepts when Gon vows he'd rather die than open his binder otherwise. Upon seeing Gon's Ren, he thinks he shows promise, but is still far from maturation, and activates his own Ren. He easily dodges and blocks the boy's attacks by reading the flow of his aura. Then, he begins to beat him down one-sidedly without using his ability.
Meanwhile, Bara faces off against Biscuit, who uses a Paladin's Necklace to revert a card into an "Accompany" and fly herself and Bara to Soufrabi. He is surprised there is no ambush waiting for him there and is perplexed by her claim she did not want him calling his friends for help. She proceeds to beat him up. Despite the injuries, Bara laughs and claims she cannot defeat him. After he manages to land a hit on Biscuit, knocking her down, she reveals her true form and hits him unconscious with a single punch to the face. Barely conscious, he asks her why she hides her true strength, but passes out before she finishes her explanation.
After presumably using the same tactic as Biscuit to relocate Sub and himself, the former assassin duels the Bomber. The two trade blows until Killua uses Rhythm Echo and then Lightning Palm to stun Sub for a few moments, with Sub mistaking the Nen ability for a stun gun. He dodges one of Killua's yo-yos, and is astounded when it fells a tree in its path. He avoids more attacks until he suffers a blow. Noticing a flaw in Killua's guard, he knocks the yo-yo off his arm and charges, landing a kick with a feint. However, Killua had intentionally given him the impression of leaving himself open and hits him from behind with a second yo-yo. Barely conscious, Sub figures out Killua's trap before the boy knocks him out.
Despite the beating he has received, Gon does not give in. Genthru realizes that to win the battle, he must break Gon's spirit. In the blink of an eye, he grabs Gon's left wrist and detonates it with Little Flower. Gon defends against the attack with Gyo, and Genthru realizes that he trained himself to able to counter that move. He goes to grab Gon's arm again, but feints an explosion and instead punches him in the abdomen, causing excruciating pain to Gon and making him cough up blood. Genthru then mocks the boy's training, but Gon continues smirking, much to Genthru's irritation. He attempts another feint, which Gon manages to see through due to Genthru not using Gyo on his own hand. Genthru then showcases Little Flower from both his hands and explains its effects on the victim's body. Faced with Gon's stubbornness, he announces he will blow off his limbs one by one.
Genthru swiftly grabs both of Gon's wrists and activates his ability, but he suddenly finds himself stunned and bleeding without understanding the reason. Horrified by Gon's aura while he charges Janken: Rock, he tries to get away from the boy, but he is unable to control his body. As he tries to back away, he trips on a root and falls, unwittingly dodging the punch. As he finds his footing, he infers from Gon's injuries that the boy used only 30% of his aura to protect his right hand and none at all on his left, instead kicking him in the chin with the remaining 70% of his output. When he hears Gon says that it has been enough, he assumes that he intends to surrender, only to be shocked when the boy declares that he will fight for real, thinking to himself that he is insane. He pretends to surrender to get Gon near him while his binder is out and crushes the boy's throat to prevent him from dispelling it, although Gon manages to defend against his ensuing attempt to knock him out. Enraged, Gon soaks Genthru with a gasoline container he had stored in a card and pulled out of the binder one minute before to nullify his Little Flower.
Genthru dispels his binder and claims that although his Little Flower is now unusable, he can still place an even more powerful bomb on Gon's body with Countdown. He explains the ability and prepares to touch Gon to activate it. Gon counters the attempt by using Janken: Rock on the ground, revealing a deep pitfall trap in which they both plummet, to Genthru's surprise. Genthru spots Gon in a lateral tunnel before the boy throws another card into the air, which, due to having been out of the binder for one minute, reverts into a huge boulder that comes crashing down. Genthru leaps into the lateral tunnel and the giant rock blocks the exit, only to find himself face to face with Gon as he charges his Janken: Rock. Genthru tries to surrender, but Gon carries through with the attack and knocks him out.
Following their respective battles, the three Bomber(s) are tied up and brought to the same open field. Genthru agrees to hand over his cards on the condition that Gon's team use "Angel's Breath" on Bara, who had been severely injured by Biscuit. Gon is healed first, followed by Bara. Despite Goreinu's protests, Gon's team spare the Bomber(s)' lives and Gon uses "Angel's Breath" on Genthru as well. The latter is surprised when a stranger touches him and says "I caught the Bomber", releasing the bomb.
- Though the name of their trio is the "Bomb Devil(s)" (爆弾魔, probably: Bakudan Ma), the group is actually pronounced "Bomber" (ボマー, Bomā) as indicated by the furigana in the Japanese text.
- A less likely translation of the kanji than the more appropriate (by context) "Bomb Devil(s)" or "Bomb Demon(s)" is "Bomb Magic".
- Genthru is the only member of the trio who doesn't have a tattoo on his forehead.
- Kazsule's Alliance believed the Bomber to be either a Manipulator or an Emitter; however, sources outside of the main series credit Genthru as Conjurer* (🖱️).