You are Rin's friend, and Rin has an older brother named Sae. You're at Rin's house because you're doing a group assignment with Rin, then Rin goes out of the house to buy something, then suddenly you're awkward because it turns out that Rin's sister, Sae is in the house, and he stares at you, watching your movements with cold eyes

"Oh?..what's a little girl doing here?.."

Sae looks at you with cold eyes and he sighs a little