|"Whatever. I didn't ask to become an airbender, you know."|
|— Ryu to Korra.|
Ryu is an Earth Kingdom citizen who developed airbending abilities following the Harmonic Convergence of 171 AG. He lived with his parents in the basement of their house, though relocated to Air Temple Island, where he commenced his airbending training, and eventually became the Air Nation tour guide for the Republic City Spirit Wilds.
Ryu was summoned from the basement by his mother upon a visit of Avatar Korra, Mako, and Bolin, who had heard that he had gained airbending abilities. He met Korra's greeting with a stoic attitude, uninterested in learning the ways of the airbenders. As he tried to retreat into his room, he was grabbed by his collar by Korra and forcefully planted on a chair at the table, where he was lectured about his responsibility as a citizen of the world to take an interest in his new abilities. Ryu, however, remained nonplussed and said he did not ask to become one, to which Korra retaliated that she did not ask to be the Avatar, yet still had her duties to fulfill. He kept on insisting she did not have to do so, maintaining an uncaring attitude about the entire situation. He aggravated the Avatar to the point where she grabbed him by his collar and started to forcefully drag him out of the house. As both Korra and his mother tried to get him out of the front door, Ryu catapulted himself back into the house by blasting the wall with airbending. As Mako and Bolin guided a frustrated Korra back to their Future Industries airship, he was slapped by his mother for having landed on her and his overall behavior.
Tired of his mother's insistence and after hearing about the Red Lotus' attack on the Northern Air Temple, Ryu decided to embrace his new life as an airbender and join the Air Nation. Two weeks after Zaheer's downfall, he attended Jinora's anointment ceremony as an airbending master at Air Temple Island.
Attacked by spirit vines
Ryu continued to reside and train on the island. He eventually became the Air Nation tour guide for Republic City's Spirit Wilds, despite maintaining his generally disinterested attitude. Before venturing inside the Spirit Wilds to give a tour to his parents and several other tourists, Ryu went over his note cards, while irritatingly shrugging off his mother's fussing over him. During his tour, he read the information off his cards in a monotonous and disinterested tone. He sighed in annoyance when one of the tourists asked if they were in the Spirit World and irritatingly answered in a negative fashion. His mood worsened when that same tourist asked if the Spirit World was in the ground below them, a question to which an aggravated Ryu gave the same response while expressing his desire to just get through the information listed on his cards. He was stumped for an answer, however, when asked why one of the vines was coming toward them, though could not understand why the tourist desired to poke the moving vegetation with a stick. After the vine grabbed the tourist, Ryu tried to sever it with his airbending, though failed, and soon he and his entire group were captured and locked inside vegetative pods, which trapped their souls in the Spirit World. They were eventually saved by Korra and, upon reentering his body and being released from the pod, Ryu tiredly noted that he felt all "spirity". Together with Jinora, he led the group of tourists safely out of the Spirit Wilds.
Defending Republic City
When Kuvira threatened Republic City, Ryu and the airbenders, along with Team Avatar, attempted to slow down the advance of her enormous mecha suit carrying a spirit energy cannon in order to give Asami and Varrick enough time to adapt the prototypes of the hummingbird mecha suits in Asami's office at Future Industries Tower. On Meelo's urging, Ryu and the other airbenders equipped themselves with balloons filled with paint. As they approached the suit, Kuvira fired at them; although the beam missed, the power it emanated was enough to throw Ryu off course and he slammed into Kai, who saved him from falling to the ground by grabbing him by the collar and hauling him up on the ledge of a nearby building. They both recovered and resumed their mission. Upon reaching the enormous mecha suit, they dropped the balloons on the suit's windows, momentarily obscuring its vision and enabling the earthbenders on the ground to tie down the suit's legs. As Bolin gave the signal, Ryu and the other airbenders blasted the suit with air currents in an attempt to topple it over. The suit managed to stabilize itself, however, forcing Ryu and the others to flee when Kuvira fire her spirit cannon at them once more. Sitting dazed on the ground, Ryu gathered his bearings, before they all retreated to Asami's office.
Defending the spirits
In the aftermath of Kuvira's defeat, Ryu joined Jinora and several other airbenders in a meditation session at the new Republic City spirit portal. Their session was interrupted, however, by the appearance of Wonyong Keum and his construction workers, who demanded that they left the premises. Ryu, refusing to leave the area surrounding the portal, which they now considered to be sacred land belonging to the spirits, supported Jinora as she told off the businessman. The heated discussion was interrupted by Korra and Asami's return from their vacation in the Spirit World, and Ryu stood by in support when Opal assured the Avatar that the airbenders were on her side and ready to help protect the portal.
A few days later, Ryu, along with Tenzin, Jinora, Ikki, Meelo, and Kai, joined Korra on her mission into the Spirit World, where she hoped to be able to reason with the spirits and convince them that the Avatar was and would always be the bridge between the spirit and physical worlds. Upon entering the Spirit World, however, they discovered that the once vibrant field of flowers that Republic City's spirit portal led to was now barren and seemingly burned down. As they explored the place, Ryu and the others were attacked by vines of the scorched spirit flowers. Defending himself with his airbending, Ryu and the rest of the party rushed back through the portal on Oogi. Before they could recover from their ordeal, however, they discovered that Raiko had ordered the United Forces to erect a perimeter around the portal, much to their dismay.
Ryu is unmotivated, somewhat lazy, and generally uninterested in most things. He is known to have a love-hate relationship with his mother, who was more than excited to get her grown son out of the house and on his own, and even threw him off her in anger when Korra failed to recruit him to the Air Nation. Initially, he was also rather mopey regarding his airbending, showing no interest in his powers and even saying he did not ask to be a bender in the first place. Even after joining the new Air Nation and getting a job, he maintained his indifferent demeanor, though he showed a more selfless side when trying to save a tourist from a rogue vine and defending Republic City from Kuvira's giant mecha suit.
- Ryu is a parody of Ki Hyun Ryu, one of the series' producers.
- Ryu is the fourth known character to have dyed their hair, the others being Ginger, Gombo, and Huan.
- Ryu greatly resembles his father, both in appearance and general flippant attitude. They are also voiced by the same voice actor.