Ryu Min-seok

In 2018, Keria began his career by joining DragonX (DRX) as a trainee support player, and in November 2019, he was promoted from trainee to the main roster. He made his debut with the team on December 26, 2019, at the KeSPA Cup, where he secured a 2–0 victory against KeG Chungnam. Keria was named the MVP of the match.

In his rookie season, the 2020 LCK Spring Split, Keria had the highest kill participation among all support players in the league at 77.4% through the first half of the regular season. At the end of the regular season, Keria finished in third in the season MVP race, earned a spot on the LCK First All-Pro Team, and received the LCK Young Player Award. DRX had a solid showing in the 2020 LCK Spring Split, finishing with a 14–4 record and on the back of a seven-game winning streak. They entered the playoffs with a bye to the second round but were eliminated in the semifinals by T1. In the Summer Split regular season, Keria led all LCK support players in KDA and kill participation, also topping the league with 401 assists during the regular season. DRX finished the regular season in second place with a 15–3 record. In the playoffs, DRX reached the finals but experienced a one-sided defeat against DAMWON Gaming (DWG), with DWG winning 3–0.

Entering the 2020 League of Legends World Championship as the LCK's second seed, DRX progressed beyond the group stage. However, their Worlds run ended in the playoff quarterfinals against DWG, mirroring their previous encounter in the LCK Summer Split Final. DWG secured a decisive 3–0 victory, resulting in DRX's exit from the Worlds tournament.

On November 18, 2020, T1 officially announced the acquisition of Keria for the 2021 season. Despite facing challenges early on in the 2021 LCK Spring Split regular season, T1 finished it with a five-game winning streak, securing a spot in the playoffs. Recognized with the nickname "The Genius Monster," Keria earned a position on the LCK First All-Pro Team for the 2021 LCK Spring Split. In the playoffs, T1 emerged victorious against DRX in the first round but lost to Gen.G in the second round, finishing the split in fourth place. In the Summer Split, T1 finished fourth in the regular season standings with an 11–7 record. Keria secured his second consecutive placement on the LCK First All-Pro team at the end of the regular season. T1 advanced to the LCK Finals in the playoffs, but faced a defeat against DAMWON Gaming, settling for a second-place finish.

In October 20221, T1 defeated Hanwha Life Esports in the LCK regional qualifier finals, securing their place in the group stage of the 2021 World Championship. Progressing beyond the group stage, T1 advanced to the knockout semifinals, where they faced defeat against DWG. In December, Keria was presented the 2021 LCK Supporter of the Year award.

In the 2022 LCK Spring Split regular season, T1 achieved an unprecedented feat by concluding with an undefeated 18–0 record, marking the first time in LCK history that a team had accomplished such a perfect run. Keria broke the record for the most assists in a single split, recording 462 assists and surpassing the previous record of 445 set by former SK Telecom T1 support, Lee "Wolf" Jae-wan. Keria's performance earned him the distinction of being named the 2022 LCK Regular Season MVP, making him the first support player to receive this honor. Additionally, he secured a spot on the 2022 LCK First All-Pro team. T1 clinched the LCK title at the end of the split by defeating Gen.G on April 2, 2022, in the LCK Spring Finals, marking Keria's first LCK championship. On April 29, 2022, T1 extended Keria's contract through the end of the 2023 season. With the Spring Split title, Keria participated in his inaugural Mid-Season Invitational (MSI) as T1 qualified for the 2022 MSI as the LCK representative. Although the team reached the finals, they experienced a defeat against Royal Never Give Up, securing a second-place finish. During the 2022 LCK Summer Split, on July 7, Keria recorded his 2,500th assist in the LCK during a match against KT Rolster becoming the eighth support player and the 15th overall player in the LCK to reach this milestone. After T1's win over DWG KIA in the 2022 LCK Summer Split playoff semifinals, Keria was looked visibly ill postgame. He expressed in an interview afterwards that he had been feeling unwell since July, with symptoms such as brain fog and dizziness. T1 lost the 2022 Summer Split finals to Gen.G, finishing in second place.

T1 entered the 2022 World Championship as the LCK's second seed. Keria reached the Worlds finals for the first time in his career after T1 defeated JD Gaming in the semifinals. However, T1 lost to DRX in the finals by a score of 2–3. After the loss, Keria was visibly upset, as the broadcast showed him shaking and tearing up. At the end of the year, Keria was named the LCK Supporter of the Year.

In the 2023 LCK Spring Split regular season, Keria earned the most Player of the Game awards, securing the Player of the Split title and becoming the first support player in LCK to achieve the recognition. Alongside the entire starting T1 roster, he received a spot on the 2023 LCK Spring First All-Pro Team, and Keria was named the regular season MVP for the second time in his career. Despite their regular season performance, T1 reached the Spring Split playoff finals but once again fell short against Gen.G, finishing in second place. With the second-place finish, T1 qualified for the 2023 Mid-Season Invitational. At MSI, T1 reached the upper bracket finals but faced defeat against JD Gaming, sending them to the lower bracket finals, where they lost to Bilibili Gaming by a score of 1–3. In July 2023, during the 2023 LCK Summer Split, T1 encountered challenges as mid laner Lee "Faker" Sang-hyeok was sidelined due to a wrist injury. Keria's, as well as the entire team's, performance dipped during this period. Upon Faker's return, T1 won their final two matches, concluding the regular season in fifth place with a 9–9 record. On August 20, 2023, Keria made his sixth LCK finals appearance, but T1 faced another defeat against Gen.G in the finals.

T1 entered the 2023 World Championship as the LCK's second seed. Keria reached his second consecutive appearance in the Worlds finals after T1 secured a victory over JD Gaming in the semifinals. In the finals against Weibo Gaming, the first game saw both teams evenly matched until the 18-minute mark, when Keria executed a move called Hostile Takeover. This play allowed teammates Faker and Zeus to secure kills that enabling T1 to establish a significant lead and ultimately secure the victory in the game. T1 carried this momentum to win the following two games as well, resulting in a 3–0 victory and giving Keria his first World Championship title. At the end of the year, Keria received his third consecutive LCK Supporter of the Year award.