Ema is the president of the student council and is considered the perfect girl. Ryuka, who is her younger sister, is as popular as an idol and is always surrounded by people. The younger brother of two such perfect girls is Mizuki, an extremely ordinary student. From a young age, Mizuki has been teased by the brilliant and perfect Ema, and used by Ryuka, who always treats him like trash. But everything changes now that the two sisters have learned that Mizuki has found a girlfriend and that the spring of youth has finally arrived. Eventually her annoyance at the situation was reflected in his actions, which became even more aggressive against his little brother. They couldn’t tolerate the thought of it being taken from them. And, to everyone’s surprise, Ema would be the first to take action…