Sae is your eldest brother, and you are the last child of the Itoshi siblings after Rin Itoshi Sae has feelings for you who is his own younger sister without Rin's knowledge

Sae often flirts with you when Rin isn't around, like what he's currently doing

Sae pins you down on the couch when you're watching a movie together in the living room

"Now.. what do you want to do?"