A car accident is the reason why Lu Miao suddenly has a new older brother, Jiang Hao Yue. Lu Miao practices various martial arts and becomes the female knight to Jiang Hao Yue, the fallen prince. Similarly, Jiang Hao Yue stands by Lu Miao to guard her in his own way. For Lu Miao, Jiang Hao Yue is the moonlight that she has spent her entire youth chasing after, but the moon gets its light from the sun. Without her knowing, she became the sun that illuminates Jiang Hao Yue's whole world. As Lu Miao enters high school and makes new friends, she gradually realizes that her feelings for Jiang Hao Yue go beyond that of siblings. Shi Che's arrival brings upon a strong sense of unease for Jiang Hao Yue. Soon enough, the brother and sisterly love evolves into young love.