Kei, a high school girl, has an unrequited love for her senpai, Kurotaki from the soccer club. When she can finally get closer to her senpai, she was disturbed by her younger childhood friend, Rui?! "I'm in a position to attack Kei anytime", "Do you still see me as your younger brother?". This guy... is cute but super cheeky! From a childhood friend to a fastball love!!