"Now guys how about instead of fighting each other we worry about the door that isn't connected to a building?" Mira honestly wanted to physically break up the fight, it's the only sure-fire way to get Naoto and Nori to stay calm. Except normally only Naoto has a weapon, she's been meaning to say something about that but no one important been stabbed yet.
"Naoto-kun, Nori-kun, doesn't that seem like fun, who knows what sort of violent things are in there?" Appeal to their violent natures that usually works.