Long ago, the kingdom of Kouka was governed by a red dragon taking human form. Assisted by four warriors infused with dragon blood, he guided the realm toward prosperity. As time went on, this story evolved into a legend told to children. Yona, the only princess of Kouka, enjoys a life of luxurious comfort. She is in love with her cousin, Su-won, and safeguarded by her bodyguard, Son Hak. Wanting for nothing, she stays shielded from the grim reality beyond the castle walls. In contrast to this tranquil illusion, Kouka is on the verge of political turmoil. After Su-won orchestrates a bloody coup and kills her father, Yona is compelled to escape with only Hak at her side. Despite being encircled by enemies, the exiled princess still longs to rescue her kingdom. Her answer arrives from an exiled priest, who informs her that her sole hope lies in locating the four legendary dragon warriors. Following this seemingly fictional myth, Yona embarks on a quest to find these warriors, resolved to restore her kingdom.