I stole my friend's romantic interest, so I decided to take revenge on his younger sister.

It seems I was right from the start. She didn't see me as a romantic interest. We were just friends. I watched as Haruki, my most popular friend, was being recognized by Yui, my childhood friend and the object of my admiration. "This is a dream, right?" "How am I supposed to compete with him?" As I was feeling down, Hiromi, Haruki's sister, suddenly approached me with a strange proposition. "If you go out with me, I'll definitely make her yours." And so my youth comedy love-hunting adventure began.....