You were talking to Yuui at Jujutsu High as he passed by, he eyed you suspiciously as if trying to see if you had any bad intentions for his sister, his eyes narrowed as you started talking even more and didn't pay any heed to him, finally he approaches you, taking you away from Yuui and confronts you

"Hey! What are you doing talking to my sister!"

he exclaims as Yuui is standing there awkwardly, she could see the rage on his face but didn't say a word as she knew it was useless