Blue/Synopsis

History
16 years prior to his introduction, Blue was allegedly born to Blast and an unknown mother. Sometimes prior to the Neo Heroes Saga, he was contacted by Fuzzy to join the Neo Heroes as the top hero and accepted, wishing to surpass his father in strength.

Supreme Hero Arc
Blue is first shown chasing Saitama, who is running away from the battle that just transpired in I-City with a monsterized Sweet Mask in tow. Worried that he is going to fall behind, Blue decides to use his one-time weapon, stating that he needs to remove his suit's limiter. However, he is intercepted by Genos, who orders him to stop and questions him on his actions. Blue frustratedly asks Genos why he would interfere in his attempt to catch Saitama, also questioning Genos on the motives of the Hero Association and Saitama's identity. He begins to remove his jacket, warning Genos that the situation could escalate to violence if he did not cooperate. Genos remarks on the high energy signature he detects on Blue's forearm, stating that it is prohibited for individuals unregistered in the Hero Association to carry weapons of that nature. Blue retorts that Genos himself resorted to vigilantism prior to registering as a hero, stating that he did a background check on every powerful hero. Blue then introduces himself as the number one Neo Hero. Genos, upon realizing this, states that there is no reason for them to fight and then begins to walk away. Blue demands to know what Saitama will do with Sweet Mask, but Genos offhandedly states that he does not know and that Saitama does not answer to anyone before leaving. Blue contemplates the corruption of the Hero Association.

Neo Heroes Uprising Arc
Blue is shown sitting in the back of the Neo Heroes leader meeting and is introduced by McCoy as the catalyst for the organization's creation. Blue states that he created the Neo Heroes to show the world what heroes truly are, adding that this was no easy task and that they would have to give it their all. 'A' expresses his surprise at Blue's young age, and Zaedats remarks that Blue is special, being Blast's son.

When several of the cities are besieged by monsters, Blue and the rest of the Neo Heroes head out to fight them. Blue's first opponent is the Demon level monster Shell King, who takes out the rest of his team members. Blue states that he needs to prepare himself better and blames himself for allowing everyone to jump in and get injured. He then expresses anger at the injuries of his teammates before jumping towards Shell King and landing a quick barrage of strikes. Shell King is unharmed by this attack and grabs Blue with its claw. Blue briefly thinks about the difficulty of Demon level threats and the trouble they give to heroes, before activating his battle suit and using his left hand to cut off Shell King's claw, breaking himself free. Blue then uses his special move Fist Cannon, instantly killing Shell King. The Shellfolk retaliate to their leader's death by attacking Blue, but he quickly dispatches them before calling McCoy and requesting medical support for his downed teammates.

Blue and McCoy have a brief discussion, with Blue stating that fighting a monster in real life is similar to the simulations, but adding that it's impossible to win 100%. He advises McCoy to communicate to the others to not be careless just because of their battle suits. He then heads to L-City due to their business district being destroyed by an explosion.

In L-City, Blue takes on the Dragon level monster Eel Dragon. He manages to dodge the monster's explosive fire breath, but thinks to himself that he's heading for the next world if he loses focus for even a second. As the two of them fight, Blue relentlessly attacks the monster, but can't tell if his blows are doing any damage despite progressively unlocking more of his suit's limiters. Eventually, Eel Dragon falls, at the cost of Blue expending all his suit's energy and losing the ability to move. He relates the series of events to McCoy, and then asks if there are any other threats in the area. McCoy informs him that the threat of Mirror in Y-City is still active with no response from Neo Leaders or S-Class heroes. Blue immediately decides to go, dismantling his suit and asking for a jet drone. McCoy attempts to stop him, expressing concern for his life, but Blue mocks McCoy for only caring about marketing and insists that he can't let other people do all the work if he wants to surpass his father.

In Y-City, Blue witnesses Saitama defeat Mirror with a single punch and notices that the bald hero is the same person who rescued Sweet Mask, expressing utter bewilderment at the situation.

During a Hero Association meeting, Blue is seen featured on the front page of a newspaper, and it is revealed by Hero Association executives that he was uninjured and able to minimize damage to the area he was fighting in.

Blue later approaches the Hero Association headquarters but is turned away from the man guarding the main entrance, who recognizes him as a Neo Hero. Frustrated by being barred from entering, Blue begins shouting, requesting a meeting to discuss his suggestions for the Hero Industry as well as something regarding his father Blast. However, he is drowned out by the Hero Name Victims Association, who approached the entrance shortly after he did. Blue turns his attention to the group, singling out Saitama due to his strength shown during the fight against Mirror. Blue asks Saitama if he's deliberately keeping his identity hidden in an attempt to build up mythos and become the next Blast, warning the caped hero that he won't back down. After some confusion between the group as to who Blue is talking to, he tells Saitama that they'll meet again on the battlefield, reiterating that his own resolve is greater than Saitama's. As he's walking out of the city, Blue runs into Genos, who comments that the Neo Hero was trailing Saitama again. Blue replies that he didn't have business with Saitama, and that he only approached the Hero Association headquarters to talk to a higher-up. He then tells Genos that he's received intel that Metal Knight has been conducting secret experiments with monsters, and that the increasing danger of monsters is being caused by someone enhancing them behind the scenes. Blue concludes by inviting Genos to join the Neo Heroes, stating that someone as steadfast as him in putting down monsters is always welcome, before walking away.

Upon his return to the Neo Heroes headquarters, Blue reenters the base, only to find Erimin and Destro escorting a chained Metal Bat. He questions them on their actions, and after Erimin's vague response and Metal Bat's warning not to trust the bodyguards, Blue begins using his lenses to scan the area. However, they are interrupted by the arrival of Fuzzy, who apologizes and explains the rationale behind cyborgification, stating that Erimin and Destro jumped the gun by attempting to cyborgify Metal Bat before the requirements were met. Blue criticizes Fuzzy and the bodyguards, calling their actions pathetic.

After the confrontation ends, Blue leaves and sits on top of a building, thinking about the future of the hero industry. He says to himself that an alliance between the Hero Association and Neo Heroes will be difficult, especially considering the internal distrust plaguing both organizations. He rethinks his strategy to get his message to the Hero Association, briefly considering contacting Tatsumaki or King, but eventually deciding on Saitama, postulating that he'll be the key to reaching the Association due to his incredible strength and participation in protests.