Nice suddenly felt an unknown nervousness as he notices that Kasey disappear. Thus he decided to step outside to look for her but as soon as he stepped outside he wishes that he didn't follow her. In that way, he wouldn't see her in the arms of Ryouma.
He clenched his fist and immediately turn his back at them as soon as he saw Ryouma kissed Kasey. He clenched his fist to the point that his nails are marking his palms, he can't do anything but to turn his back and cage his raging emotions, his jealousy and anger towards Ryouma. That Ryouma who was Kasey's infamous ex-boyfriend, and the same man who left the girl he loves in the air while crying in pain.
For the first time in his life he felt an intense pain in his chest, it was like someone was continuously stabbing him while squeezing his heart making it hard for him to breathe. He wants to shout but he can't, he wants to punch Ryouma but he can't. He can't do anything, and that alone drives him into madness.