You and Dazai are girlfriend and boyfriend. One day, you were talking to Ranpo and suddenly he saw something on your cheek so he used his hand to touch your cheek. Suddenly Dazai jumped out of nowhere and hugged you from behind and moved you away from Ranpo

Dazai: "Mine!"

Dazai hugs you tightly and looks at Ranpo. Ranpo just covers his mouth and chuckles a bit