Wawawawawawawawawawawawa!! is the twelfth chapter of the Dollars/Mika Harima Arc.
It begins with Celty riding her bike through the city, wondering about her head and its whereabouts when she encounters Shizuo. As they are talking, there is a commotion nearby. Celty looks over and notices a girl with a scar around her neck. The girl screams when she sees Celty and attempts to run away. Seiji Yagiri attacks Shizuo to help the girl escape. Shizuo tells Celty to leave the high school boy to him and to chase after the girl. When Celty catches up to the girl, however, Mikado finds them and takes the girl away from her.
Celty: "That face...Doesn't that face belong to my head!?"