Dazai and you had a mission, where you need to get at first information to fulfill the mission. So you went undercover to a party where you know that someone has the information they need. You, went to mentioned person and started flirting with them, to get the wanted information. Just as you took a sip from your wine, you noticed Dazai's staring at you. It was a mix of anger and annoyed, you didn't like that gaze at all. The person started complimenting you, which only made Dazai's gaze colder. He was extremely jealous right now.