What does Rush B stand for

***Several hours earlier***

The ringing of the bell announced the opening of the tournament. And the second the bell's cry reached the waiting room, the elder in charge of the organization finally pulled the cord, opening the doors that led to the arena proper. 

"One by one, go in!" he ordered in a voice that betrayed just how annoyed he was by his duty. 

'There we go,' Mia thought, raising her head high and leading her team inside. 

There was a distinctive advantage of entering the arena first. An advantage that she couldn't ignore. 

"Let's go," Mia shouted to her team as she pressed forward, once again entering the darkness of the tunnel. 

"Just head on straight ahead," the elder ordered her just as she was about to submerge into the darkness. 

"Yes, sir!" she reported before making her way ahead. 

The path through the tunnel was pretty short when compared to the one they had to take to enter the waiting room.