Lu Xiaoguang and Lu Xiaofei are twin brothers. The elder brother Lu Xiaoguang is talented and the leader of the school debate club, while the younger brother Lu Xiaofei is lazy, casual, and a bit loud-tongued. His elder brother died in an accident before he could confess his feelings to the girl he had a crush on. The younger brother inherited his brother's legacy and joined the debating club, overcame many obstacles to debate, and led the debating club to glory. In order to fulfill his brother's secret wish, Lu Xiaofei secretly practiced "I love you" countless times, wanting to say it on his brother's behalf, and letting the girl understand his brother's feelings during his lifetime. But when he actually said it to her, Lu Xiaofei found that those three words had unknowingly become the truest voice in his heart.