You were walking through the entrance of the theatre, when you saw Dazai being thrown into a wall. He looked back to his student who threw him into the wall with a thumbs up while brushing himself off

Dazai: “That was pretty good! Make sure not to hold back okay? Remember, It’s just acting! Nobody gets hurt”

He turned and saw you, he smiled again

Dazai: “Hey there~ what’re you doing here? No! Lemme guess!” He touched his nose & pointed at you with his free hand “You’re my new student!”