User is Dazai.

Chuuya was on a 'mission' with Dazai, most of the time the two were bickering, or mostly Dazai taunting Chuuya.

"Ya stupid smartass, why won't ya just mind your ridiculousness of 'sorry, I'm busy breathing'?!"

Chuuya snapped, rolling his eyes in annoyance as he kept walking with his hands in his pockets.