Genthru is one of the players of the game Greed Island. This game, specially designed for Hunters, can only be accessed using Nen. The objective of the game is to collect cards. Whoever collects all the cards wins the game, and can choose to take three of the cards out of the game.
Genthru appears working with a group of 'weak' players who believe working together will allow them to get all the cards. They largely succeed, collecting a large number of cards. As they come together to celebrate, Genthru asks to make an announcement.
He reveals that he is the Bomber, a player that has been terrorizing the game lately. He has planted bombs on all of them using his ability 'Countdown'. It can only be deactivated if someone touches him and says 'I caught the Bomber'. Someone tries, and Genthru blows their face off using his 'Little Flower' ability. He then says that he will deactivate the bombs if he's given all the cards they've collected. He then leaves the game, reuniting with his henchmen, Sub and Bara.
Someone comes to negotiate with him, but Genthru will have none of it. He blows his head off and gives it to the rest of the group in a plastic bag.
The players decide to give Genthru the cards. They hand them over, but Genthru does not keep his part of the bargain. He detonates the bombs with help from Sub and Bara.
A coalition of players form dedicated to taking Genthru down.
Tsezguerra makes a deal with Gon and Killua - if they hold off Genthru for two weeks, Gon and Killua will hand over some rare cards.
Tsezguerra keeps his end of the bargain, distracting Genthru, Sub, and Bara for the allotted time period.
Genthru them comes after Gon.
Sub fights Killua, and Bara fights Bisky. Gon is up against Genthru.
Genthru easily knocks him around. He blows up both of Gon's arms using Little Flower. However, Gon sets off the trap he had planned, trapping Genthru in a small cavern. He then uses jajanken on Genthru, very badly hurting him.
Genthru, Sub, and Bara are captured, and Breath of Archangel is used to heal their wounds. They are left tied up in Greed Island.
A strong Nen user, Genthru has heightened strength, agility, and durability. He is an accomplished fighter, giving even a two-star hunter pause.
Genthru is a conjurer, but he is capable of using other nen groups (for example transmutation in Little Flower)
His primary abilities are 'Little Flower' and 'Countdown'.
In Little Flower, Genthru detonates part of his aura. He protects his own hands with large amounts of aura. This move is strong enough to blow off limbs.
In Countdown, he places bombs by using the key phrase 'Bomber'. The bombs are armed when he explains how his power works. They can only be disarmed if someone catches Genthru and says 'I caught the bomber'. These bombs are extremely powerful, and cannot be protected against with Nen (and even a Nen exorcist could not completely remove the bombs). Multiple detonations can be achieved if Genthru presses his thumb against Sub and Bara's and says 'release'