Un is quite straight forward in his ways. Although he is found to be apparently rude and critical (remark by Yu-Hwa), he has a caring nature. He has shown to be anxious about Yu-hwa to quite some extent and later revealed having come to much friendlier terms with him. Un has revealed to Yu-Hwa that he has a crush on Ye-Rin.
Un Ga is of half-breed Another species. Like Ye-Rin, Un joined Hon when he was very young. He went through intensive special training to gain the battle skills he has now and is an elite member of the Hons. He is usually partnered up with Ye-Rin in missions.
Un first appears with Ye Rin when Mase comes to deal with Yu-Hwa and Detective Park who are investigating events related with anothers. He strikes down Yu-Hwa so that he could be taken to their base for interrogation but is amazed and annoyed as Yu-Hwa manages to get back up like a zombie no matter how many times he strikes normally. So he enhances to make an impact. After Su-Jin Ji tells them to let Yu-Hwa go, he takes him to his cafe and tells him to stay away from them before departing.
However, one more attack on Yu-Hwa by battle type anothers leads him to Yu-Hwa's side to aid. When Detective Park gets kidnapped, he and Ye-Rin take Yu-Hwa along with them in a search party. He and Ye-Rin fight off the Salamanders. He also finishes off the one who has been fighting with Yu-Hwa. Then they go to the Salamander base where they meet Jacra. There also they fight with Salamanders until Jacra takes a particular interest in Yu-Hwa. They manage to return with Detective Park safe and Yu-Hwa bestowed with plenty of injuries.
Un drops by at Yu-Hwa's cafe in search of Ji-Woon Kang. Yu-hwa lies to him to save the child but when he learns about the lie, he rushes towards the cafe. Finding all at sixes and sevens, he looks for the two runaways. He doesn't even report to his superiors as it might get things hard to Yu-hwa. Then he finds the Another who chased Ji-Woon in an injured state and realizing that Yu-Hwa is okay, he kills the another. Later he catches up with Yu-hwa in the hospital and also meets Ye-Rin who was tipped off by Ji-woon about Yu-Hwa's sudden health issues. Admitting Yu-Hwa in the hospital, they discuss and concur not to inform their higher-ups about it least Yu-Hwa gets in trouble. However, they find him gone and hurry to catch up. Yu-Hwa convinces them to take him along in pursuit of Ji-Woon. As Un and Ye-Rin fight the anothers cornering Ji-Woon, Yu-Hwa runs after the kid who has hoodwinked them taking the stone of healing to his grandfather. Un and Ye-Rin meet them after they have reached the hospital. Later they take back the stone after Yu-Hwa uses its powers to heal Ji-Woon's grandfather enough for the kid to hear his last words.
Un appears by Yu-Hwa's side again when the Reapers attack the latter. He fights all of them but is outmatched. Yu-Hwa's awakened power and prompt use of Sa-Ryun's spheres save their lives. However, when Un reports this incident to Mase, the latter decides to keep Yu-Hwa under surveillance. Mase also intends to capture the Atran fugitive, Sa-Ryun by using Yu-Hwa as a bait.
Un accompanies Yu-Hwa to his cafe and also helps him with the repair work. Although he works under Mase's order, Un turns off the surveillance bug and reveals Mase's intention to Yu-Hwa. To his surprise, Yu-Hwa has been aware of the trap and reveals to Un that he is taking longer to fix the cafe just to keep his 'Hyuung' away. Suddenly an Atran fighter walks into the cafe and introduces himself as Lecter. He wants Yu-Hwa to spill the beans about Sa-Ryun. Un tries to stop Lecter but is no match for him. He ends up severely injured and Yu-Hwa is saved by Sa-Ryun's intrusion. After the fights end and Yu-Hwa absorbs Lecter's Orb of Power, he remembers Un who gets up from the collapsed portion of the cafe. Un is helped out by Yu-Hwa and admitted to the hospital. He asks Mase about the Pandora's Box (which he heard mentioned by Sa-Ryun) and Su-Jin explains about it. The latter days pass with Un watching over Yu-Hwa's training with Ye-Rin. He is somewhat disappointed in finding no apparent changes in Yu-Hwa's ability.
After Un recovers from his previous injury, a sudden attack is launched on Hon. Atran troops barge into the office building and Hon agents defend. Un joins the defense and they manage to subdue the Atran soldiers. He then reports back to Mase who, with Ye-Rin, has been on his way to check if Su-Jin has made it safely to the bunker. There they find Su-Jin and Yu-Hwa catching a peaceful nap.
With the invasion and post-invasion damage control over, Un accompanies Yu-Hwa to the renovated cafe. Although he was told to keep it a secret, he tells Yu-Hwa that Mase has personally funded the renovation as a token of gratitude for saving Su-Jin Ji.