Emergency Summons
While the Inter-High Tournament was taking place, specifically while everyone was having a good time at the mini-festival right by the edges of the Inter-High Stadium, the SAO sent out a phone call to every available superhero in Japan.
This phone call was an emergency summons. And to say the least, an emergency summons is quite rare when it comes to the SAO. With the abundance of strong superheroes currently, they don't really need to sound the emergency summons unless absolutely necessary. Petty crimes such as robberies or snatchers are all dealt with by the police or a low-ranking superhero.
"What do you think?" Tatsuki asked just when he closed the door behind him. It was a normal afternoon with fair weather so the last thing they were expecting was the summons from SAO.