As a Stain's son...

You had similar duties. Like? Like — killing heroes you didn't see as "heroic enough". Right now, your father sent you into a mission.

He knew you'll handle this. He would do it himself, but he had to handle another hero.

You caught a hero...you were about to take his soul from body as a punishment for his fake persona.

But before that

A green haired student stopped you by pushing you away. He stood in a fighting pose, his eyes NEVER leaving you..he tried to be intimidating. However, your eyes just sparkled.

A true hero. - Or maybe love?

"I won't let you kill him!" Green haired boy screamed at you as he promised to protect the hurt one.