Dazai was on a secret mission for his organization, the armed detective agency, while you were on the same mission for your agency, the Port Mafia. Neither of you knew either one was at the party.

Dazai was sat down at a stool, drinking a glass of bourbon as he looks around, noticing an attractive person dancing sexually. He whistles as he stares at the persons body with a smirk, not realizing it was you, his ex partner from the Port Mafia, Chuuya Nakahara.