Lee "Zefa" Jae-min began his competitive career on June 21st, 2013 when he joined NaJin White Shield as their new starting AD carry. He played in his very first OGN during HOT6iX Champions Summer 2013, where he and his team made the quarterfinals but lost 3-0 to CJ Entus Frost.
Shield's next tournament was PANDORA.TV Champions Winter 2013-2014 where they lost 3-1 to Samsung Ozone in the semifinals and then lost 3-1 to the KT Rolster Bullets to place 4th overall. Next, they attended HOT6iX Champions Spring 2014 and made it all the way to the finals but ultimately lost 3-1 to Samsung Blue. Their final OGN of the year was HOT6iX Champions Summer 2014 where they lost 3-2 in the quarterfinals to the eventual champions, the KT Rolster Arrows. Shield earned enough circuit points to qualify for the 2014 Season Korea Regional Finals and miraculously ran the whole gauntlet, culminating in a 3-1 victory over SK Telecom T1 K. This key win earned them a spot at the 2014 Season World Championship where they came out of their group in first place but were swept in the quarterfinals 3-0 by OMG.
Due to changes to the OGN rules, Shield and their sister team, NaJin Black Sword, were forced to merge to form NaJin e-mFire. During SBENU Champions Spring 2015, Zefa shared the starting position with the former AD carry from Sword, Ohq. NaJin's poor performance in Champions ended when they placed sixth overall and failed to make the playoffs. NaJin placed fifth in the regular season of SBENU Champions Summer 2015 and qualified for the playoffs but they lost in the first round 2-1 to the KOO Tigers. They earned enough circuit points to make it to the 2015 Season Korea Regional Finals but lost 3-0 in the first round to the Jin Air Green Wings. However, Zefa did not play in playoffs or the regionals. Zefa left NaJin in November.