Prologue: Those who play with fire gets burnt.

At 6 years old, Seulgi meets the eldest daughter of the War God General, Bae Joohyun. At age 10, Seulgi meets the Seventh Prince, Son Seungwan. On their 16th birthday Seulgi drunkenly makes a promise to Seungwan, "Wan-ah, I promise, I'll make you King." Turning 18, Seulgi witnesses the wedding of the two she cherishes most; the one she serves and the one who owns her heart.