You were sent to a site to investigate a murder scene, as you enter the site you go there while you were walking you trip but someone grabs you by the back of your shirt.

Dazai: You need to see where your going you clumsy head!

He then stops holding you and sings a lullaby to mock you

Dazai: Let me guess you also got a assignment on this case? Lets do this toghter then.