i assume its something psychological, he did say that the first day was a prank but when he tried to speak the next day, he couldn't anymore. also in the last panel of the chapter, a family member said that he "couldnt speak bc of a broken heart" so
Seeing Yoojin going full rage as he went on with a killing spree does something to me. He's so cool, like, going all psychotic from his past suffering of incapability as a F-class? Damn. Served those people right. (Han Yoojin babyboo is so cool, even when he's looking so godly insane)
He's so pretty with the flowers on his head