Siblings is the fifty-fourth chapter of Hideyuki Furuhashi and Betten Court's Vigilante - My Hero Academia: Illegals.
The story goes back two minutes before the explosion. In the police helicopter, Shota Aizawa asks Naomasa Tsukauchi to call All Might to come to the place to help because, although it seems that the heroes are winning and Best Jeanist’s Quirk is holding up the tower, the threat has not yet over, as there is always the possibility that the enemy has another trick up their sleeve.
The detective is somewhat reluctant to summon the number one hero for a mere precaution, but Aizawa tells him that, although his request goes against regular police procedure, in that they are dealing with an unprecedented crisis, with thousand lives at stake, so it's not the time to get carried away by the regulation and normatives.
Naomasa agrees to Aizawa's request and calls All Might, who at that time he is in a meeting at the Might Tower as Yagi Toshinori. Upon hearing Naomasa's call, Yagi apologizes and goes to a secluded area to talk to him. Naomasa tells him that the Tokyo Sky Egg is in trouble, but before he can clarify him the situation, Yagi hears a big explosion on the phone.
In the distance, Number 6 looks satisfied as the building begins to collapse, with thousands of people inside. At that moment, he says that only a god could save them.
Yagi does not stop asking what is going on, but his questions are not answered by Naomasa, who watches impotently as the building collapses, with thousands of people inside, including his sister Makoto Tsukauchi. At that instant, he begins to remember moments of his childhood with her and how important she is to him. Then he desperately asks All Might to save his sister.
Upon hearing this request for help, the number one hero immediately leaves the Might Tower to save everyone.
All Might takes only a few seconds to reach the place and, in a flash, he smashes the remains of the tower out of the way, flatten the ground, bring animals to safety and landing the Tokyo Sky Egg dome safely. He even finds the time to take some selfies with people. The bystanders are stunned by that inhuman feat.
Meanwhile, Captain Celebrity and Koichi Haimawari continue to fall. Koichi sees All Might and greets him. When All Might sees them, he immediately rescues both. All Might congratulates Captain Celebrity for what he has done and signs Koichi's hoodie. Everyone starts cheering for All Might.
Only one person is not happy about what has just happened.
On top of a building, Number 6 feels increasingly furious to see how his last act of revenge had been totally ruined by All Might’s intervention.