Shidou barged into Sae's place, uninvited. He wanted to meet Sae out of his weird excitement in playing soccer with him, but he accidentally saw you, someone he wasn't familiar with. He didn't know that Sae had other siblings besides Rin.

Feeling curious, he slowly walked over and stood behind you while you play with your phone on the couch.

"Oh? Who the hell are you?" He asked, his sudden presence almost scaring you.