Suehara Maru and Kuroha Shida have been best friends since childhood. Kuroha, who is cute, friendly, and adored by many, exudes an older sister vibe. She has a long line of suitors clamoring for her attention. However, when Kuroha finally professes her feelings to Suehara, he turns her down outright. She doesn't fit the bill for his romantic ideal because he already has his sights set on Shirokusa Kachi, the school's famous author and heartthrob. Suehara thinks he has a shot with Kachi after having a fateful encounter with her. But his hopes are dashed when he discovers she's taken. Blinded by disappointment and frustration, Suehara dwells on what could have been until Kuroha pops up with a plan for revenge.