Season 1: Chapter 1 - Chapter 60
Su-jin first appears before Han Yu-Hwa  asking him for his cellphone to make a call. When Yu-Hwa feels surprised about her sudden appearance and demand, she reassures him that she would only make one phone call and compensate him for the trouble. She feels shy when Yu-Hwa gives her cellphone easily and tells her to take her time. A sudden breeze blows away her hat towards mid-road and she follows to catch it. However, she ends up right on the way of a big truck which has been coming with great speed. Yu-Hwa jumps in right on time to save her. He takes on the full impact and both of them end up in hospital. Su-jin gets away with a few minor injuries and stays in the VIP room#1 for time being.
Later in the hospital, she is attacked by an Another  but couldn't move. Yu-Hwa saves her again and fights the Another to make room for her escapade. She brings her guards with her as the Another flees.
Afterwards, she visits Yu-Hwa along with Mase, and thanks her 'Oppa' for his continuous aid.  After the truth about Anothers and their nature of feeding on abilities is revealed to Yu-Hwa, he is warned to stay away from anything related from then on. Su-Jin then promises to give Yu-Hwa whatever he wants as a repayment for saving her life but is dumbfounded when he asks her to find him a girlfriend.
However, within a short while, Su-Jin Ji finds Yu-Hwa has been involved in the Another issue again and has been brought to Hon headquarters for interrogation. She personally intervenes to release Yu-Hwa , to which Mase reluctantly agrees. But her 'oppa' again ends up with another encounter with Anothers - this time, the Salamanders have kidnapped Detective Park. Yu-Hwa demands an explanation about Hon since his life seems to be continuously invaded by Anothers. Su-Jin explains that Hon exists to co-ordinate and maintain the harmonious relationship between humans and Anothers and she is in charge of Hon. At this, Yu-Hwa requests her to allow him accompany the agents to pursue the kidnappers. Su-Jin tries to convince Yu-Hwa that this would put his life on jeopardy but her oppa remains adamant. Although reluctant, Su-Jin allows it after Mase approves of the suggestion.
After the Salamander mission has been completed, Su-Jin Ji offers Yu-Hwa to join Hon ; not for his service but for his protection. She surmises that the recent attacks prove that the anothers have taken interest in Yu-Hwa. Su-Jin gives Yu-Hwa time to think and decide and also offers to financially support him.
Su-Jin, meanwhile, is persistent in her efforts to find a girlfriend for Yu-Hwa and sets up a date for him with Ye-Rin. However, Yu-Hwa messes up her plan by failing to realize it was a date. She scolds him well for it the next time Yu-Hwa visits Hon office.
Other worrying events come to pass as Su-Jin receives affirmed information that Atran has been pursuing Sa-Ryun who has hidden in their (HON's) territory. She the difficult position they are in when a more concerning issue occurs: the pursuers are near Yu-Hwa's cafe. Seeing her concerned, Mase sends agents to check on Yu-Hwa where another fight takes place. After that incident, Hon finds out the existence of a mysterious relation between Yu-Hwa and Sa-Ryun. Su-Jin hears about the latter events - fight between Sa-Ryun and Mase, Yu-Hwa absorbing Lecter's Orb of Power and Sa-Ryun's tips from Mase. She learns that Atran intends to attack Hon. Furthermore, the Atran heir had found out the location of Pandora's Box but before he could reach it, Sa-Ryun had killed him. At the mention of Pandora's Box, she becomes alarmed. Yu-Hwa inquires about the significant object and she describes the box as a dangerous object. Un raises questions regarding Yu-Hwa's unusual power absorption. Su-Jin is also puzzled by this ability, however, they all agree that it might be a good thing for Yu-Hwa to get stronger. Yu-Hwa is allowed to train with Hon agents while Su-Jin watches over them - adding to the list of worries in her already troubled mind, suspecting Atran might launch an attack on them anytime.
Su-Jin disapproves of Mase's continuous suspicion about Yu-Hwa. But they soon have more important thing to worry about as Hon is under sudden attack. Atran troops make it inside the office building. Su-Jin Ji is led down a hallway by Mase, when suddenly, Atran agents appear before them and target her. Mase protects Su-Jin from the attack and counterattacks the Atran troop. However, Zed, a highly-dangerous Atran Another appears in front of them and demands the key to the Pandora's Box: Su-Jin Ji. At this, Su-Jin Ji is compelled to has to proceed to the underground bunker, guarded by two other Hon agents while Mase remains behind to fight Zed.
Su-Jin is about to reach her destination when the ceiling gives in and down comes another highly dangerous another, Guight. Su-Jin's guards are easily defeated by the new enemy. She is then asked by the Another to go with him but the Hon princess refuses to give herself up to the enemy. Suddenly, Yu-Hwa appears and kicks Guight away to protect Su-Jin. The two of them are saved from Guight's wrath by Ye-Rin's arrival. Ye-Rin asks Yu-Hwa to take Su-Jin Ji and escape while she remains to fight the Another. Su-Jin Ji agrees with the plan and persuades Yu-Hwa to accompany her.
Su-Jin and Yu-Hwa are talking about Ye-Rin while running through a corridor. Suddenly, they hear Anothers approaching and halt on their tracks. Su-Jin leads Yu-Hwa on another route leading to the emergency underground bunker since it appears that Atran has taken control in most of the building. She explains to Yu-Hwa that she is the key to Pandora's Box and so her fate is to die before falling into enemy's hands. She is scolded and lectured by her 'oppa' for having thoughts like that even though she is just a kid. At this, Su-Jin gets quite emotional. They are, however, interrupted by a sudden voice and look around to see Jacra and Tar standing before them. Jacra reveals that although they are unrelated, Atran offered them a deal just to capture the Hon princess. Although surprised, Su-Jin Ji supports Yu-Hwa's gamble on revealing the Pandora's Box issue to Jacra. Tar questions the connection between the invasion and Pandora's Box and Su-Jin reveals that Atran is attacking to capture her because she is the key to Pandora's Box. Although reluctant to harm a child, Jacra's opinion is to kill the Hon princess so that the Pandora's Box can never be opened. However, Yu-Hwa's determination to save Su-Jin interests Jacra and he proposes a deal: they'll walk away if Yu-Hwa can defeat Tar in a fight. Su-Jin Ji tries to discourage Yu-Hwa but he is adamant to take the only course to ensure of her safety. So, both Su-Jin and Jacra witness the fight. After Yu-Hwa wins his side of the bargain, Jacra and Tar take their leave.
Finally free from danger, Yu-Hwa collapses to the floor and Su-Jin immediately approaches her "oppa". Smiling, Yu-Hwa points out that he kept his promise to protect Su-Jin. The child smiles back at him and they continue on their way to the underground bunker. When the Atran forces are subdued and retreating, Mase, Ye-Rin and Un arrives head towards the bunker and find Yu-Hwa and Su-Jin Ji sleeping peacefully leaning on each other. Afterwards, Su-Jin Ji undertakes the almost routine task (since Yu-Hwa has a knack of getting injured) of visiting Yu-Hwa at the local hospital with Mase.