Princess Yona of the Kingdom of Kouka, with her unusual red hair, has lived a comfortable life in Hiryuu Castle protected by her father King Il, who hates conflict, and her childhood friend and guard, the young general Hak. Yona is overjoyed when her cousin Soo-Won, whom she has loved since childhood, arrives for her sixteenth birthday banquet.

“We'll go anywhere as long as it means you'll live.” As Yona is dazed by the suddenly rebellion at the castle, Hak runs to her rescue. Also known as the “Thunder Beast of Kouka Kingdom”, Hak protects Yona, and with a single lightning-quick strike from his blade, he dispatches the mercenaries attacking them on after another.

Hak protects Princess Yona as they make their way through the mountains. Having lost her will, Yona is only able to follow behind Hak. Hak painfully watches Yona grow weaker

At the end of their difficult escape, Yona and Hak arrive in Hak's hometown of Fuuga, the capital of the Wind Clan, where Yona receives a warm welcome

Hak is accused of murdering King Il. In order to protect Yona and the Wind Village, he gives up his title of chief and decides to wander alone.

Though Hak continues to fight off the soldiers pursuing him, a poison prevents him from fighting like his usual self

Yona and Hak, covered in wounds from protecting the princess, are saved by the Priest Ik-Soo and his caretaker Yoon living on the valley floor.

Ik-Soo suddenly announces he will travel with Yuna and Hak to see the world. Yoon is upset and unable to contain his anger. Though Yona and Hak understand his feelings, they are unable to do anything but watch in silence

The words of god conveyed to Yona through the priest Ik-Soo are to find the four Dragon Warriors of Kouka Kingdom's Legend of the Four Dragons

Yona and her friends arrive in the village where the White Dragon lives. The proud villagers who have protected the power of the White Dragon and passed it down through generations of White Dragons believe Yona may be the descendant of the Hiryuu King who employed the first White Dragon when they see her red hair.

oined by the White Dragon Ki-Ja, following his claim that Dragon Warriors can sense each other, Yona and her friends begin their search for the Blue Dragon. However, even with Ki-Ja's power, they are unable to determine his exact location

In their search for the Blue Dragon, Yona and her friends visit a hidden village carved from stone. Though Ki-Ja insists the Blue Dragon is there, the villagers claim there is no Blue Dragon.

The five search for the green dragon warrior using Shin-Ah's farsightedness to scout ahead. They encounter a dilapidated village and a sickly man who criticizes the late King Il. Meanwhile, Su-won visits Chishin, the capital of the Earth Clan, and meets with Lord Li Geun-Tae, who is not impressed by Su-won. Su-won declares they will hold a war-game festival at Chishin in a week.

The war game is held. The participants are divided into teams with Su-won and General Geun-tae leading the white and red teams respectively. The objective: to score the most points by breaking the plates of the other team. Su-won's strategies and hidden ferocity impress Geun-tae, whose team manages to win more points than the white team despite all their plates being broken. Su-won leaves the city with his cohorts, having stimulated demand for Geun-tae's wife's tea in a neighboring land, re-invigorated production in the earth tribe's mines, and inspired the earth tribe's people anew of their leader's strength.

Yona and her companions reach Awa Port. Hak enters the city alone and without realizing it, meets the green dragon warrior, Jae-ha. Jae-ha moved to the city thirteen years ago and joined a band of good pirates lead by Captain Gigan. With the help of Jae-ha's jumping power, they sink the drug-carrying boats which belonged to the lord of the region, Yan Kumji. Jae-ha senses that the white and blue dragons have come to the city. As he wishes to avoid his destiny, he quickly disappears whenever they are near. When a citizen was harassed by corrupt officials, both he and Hak help. After meeting Hak, Jae-ha decides to recruit him.

Yona and her companions continue their search for the green dragon warrior, encountering more corrupt officials. As Jae-ha pursues Hak, he unwillingly meets Ki-ja. Jae-Ha refuses to join them and flees again, soon-after finding Hak. While persuading Hak to join the pirates, he meets Yona and discovers that she is the master of the four dragons. He turns down Yona's invitation to accompany her on her journey. Yona, while gracefully accepting his choice, is however determined to help the town and asks to meet the Pirate captain. Jae-ha brings them to Captain Gigan, who approves of Hak and the other two dragon warriors' fighting ability. Yun, while lacking fighting ability, speaks of his other skills. Yona cannot think of any skills she possesses, but impresses the captain with her resolve. The captain decides to give her a life-threatening task to prove herself.

"Maybe it's because you don't really want her." Captain Gigan agrees to allow Yona to fight alongside her pirates if she is able to pick the "senjuso," a rare medicinal herb growing in the middle of a sheer cliff, without anyone's assistance. Yona's companions try to talk her our of accepting such a dangerous task, but Hak, who understands Yona's emotions, desperately suppresses his desire to stop her. Jeaha leads Yona to the seaside cliff where the senjuso grows. She gathers her courage and begins walking down the narrow path. However, the gusting wind and waves relentlessly assault Yona...

"Why are you always so reckless, Princess? Sometimes I wish I could tie you up..." Sensing the impending battle against Kumji, the pirates steel their resolve. Meanwhile, Yona heads into the town for reconaissance with Jeaha and happens to spot Lord Kumji. Based on the stories of the townsfolk, Jeaha determines the day of Kumji's human trafficking deal with the Kai Empire, Kouka Kingdom's neighboring country. With Jeaha's report, the pirates immediately begin working on a strategy under Captain Gigan, when Yona suddenly says the unthinkable.

Yona and Yun, who willingly entered Kumji's store as bait to help rescue the captured women, successfully infiltrate the ship transporting the women, where Kumji appears before them.

"Why? Why am I so afraid? She's just a little girl..." While suffering injuries, Yona and Yun successfully complete their task, and Jeaha rushes to their aid to fight against hordes of attacking mercenaries. Watching Jeaha fights, Yun realizes how truly amazing those who possess the strength of the dragons are. Sinha joins the fray, and the mercenaries continue to fall. Meanwhile, Hak and Gija remain behind to fight with the pirates, overwhelming their enemies with extraordinary strength. Realizing he is at a disadvantage, Kumji tries to flee so he can recuperate...

"You're not the frail princess you used to be." Hope returns to Awa after defeating Yan Kumji, and the townsfolk and pirates throw an extravagant party to celebrate. Jeaha steels his resolve. Yona decides to leave Awa and conveys her desire to her companions.

"Miss, what do you want to do with the Four Dragons?" Yona and her companions continue their journey to find the fourth and final "Yellow Dragon" when they encounter a traveler named Jeno. He is the "Yellow Dragon" they have been seraching for.

The blue dragon warrior, who experienced a voice telling him to protect Hiryuu when he touched Yona, while recognizing Ki-Ja as the white dragon, is dazed and escapes into the caves. Yona and Yun enter the caves, leaving Hak and Ki-Ja behind to deal with the villagers. They find the agitated blue dragon warrior, and Yona calmly asks him to be her ally. The blue dragon warrior tells her to leave, and they return to Ki-Ja who is holding back the hostile villagers. An earthquake traps the villagers with Yona, Ki-Ja and Yun. A villager explains the curse, until the blue dragon warrior enters. Out of fear, the villager strikes the blue dragon warrior, knocking off his mask.

The blue dragon warrior retrieves his mask and begins digging a path out of the cave. The others join him and Hak starts digging from the outside. Hak finally breaks through and reunites with Yona. Yona again asks the blue dragon warrior to travel with them and he accepts. They set off, but Ki-Ja collapses from exhaustion so they stop to make camp. Yona gives the name "Shin-Ah", which she says means moonlight, to the blue dragon warrior. When they awake the next morning, Ki-Ja tells Yona he can sense the green dragon warrior.