Sa-Ryun is a mysterious character whose true goals are unknown. He was a Hunter (assassin) for Atran but had betrayed them. He had killed the Atran heir (who found out the location of the Pandora's Box) before he fled . Subsequently, Atran sent forces to pursue him. Whilst fleeing from his pursuers, he arrived at Hon territory and was drawn to Yu-Hwa's crystal's power.
Sa-Ryun is androgynous by appearance but originally he is a male character. His androgynous looks backed by his other feminine characteristics (long nails & red lipstick) often make people mistake him for a female. He has waist-long, white hair and crimson red eyes. When he glares, his pupils become slits similar to snake eyes.
Sa-Ryun is cold and manipulative. He does lose his temper when people mistake him for a female or someone dares to disobey him. He believes one can only claim a prey when one is strong enough to have the prey to oneself.
He manipulates Han Yu-Hwa into believing that he's helping him. In reality at first, for him Yu-Hwa was nothing more than a prey. Later though he feels some attachment towards Yu-Hwa. He considered to kill him painlessly rather than Yu-Hwa being continuously falling victim to attacks from anothers. However, Sa-Ryun starts to develop certain affection for Yu-Hwa thinking he is quite funny and interesting. He reveals that the attachment results from Yu-hwa addressing him as 'hyung'.
From deep inside a forest, Sa-Ryun feels the presence of a high purity crystal when Han Yu-Hwa is hit by the truck.
Sa-Ryun feels that presence once again when Yu-Hwa subconsciously uses his powers to fight an another in his cafe. Sa-Ryun tracks him down, and finds him unconscious. He saves him from the Another. When that Another gives up on his prey and is about to leave, Sa-Ryun reveals his intention of using the Another as a nutrition for himself. But the Another escapes when Sa-Ryun shifts his attention to a half-awake Yu-Hwa. Later on, Sa-Ryun introduces himself to Yu-Hwa as his savior. He gives him a glove, saying that it would hide his abilities from Anothers. Before taking his leave, he warns Yu-Hwa to keep their meeting secret.
Some time later, Sa-Ryun feels surprised when Yu-Hwa uses his powers. He finds the ability to be much more impressive than he originally thought. He tells himself that he will let Han Yu-Hwa develop his powers so that he can steal them when they reach maturity. He takes on the responsibility of training Yu-Hwa. Although it enhances the stability of Yu-Hwa's powers, it does little to mature it.
Sa-Ryun remains absent from the cafe for awhile. During that time, he has been evading Atran pursuers. The devastated battlefield is later investigated by Mase who confirms Sa-Ryun is in Hon area with Atran pursuing him.
By the time he shows up again in the cafe, Yu-Hwa has joined Hon and fought against more Anothers. His powers have also grown. Sa-Ryun is asked by Yu-Hwa to stay at his house but declines the offer knowing that Atran is after him. Sa-Ryun gives him some of his powers (enough to take four/five shots of his spheres) to use if necessary now that his chances of encountering more anothers have grown. After Sa-Ryun leaves, his trail is followed by his pursuers. He later hunts his pursuers down and learns that they have already been injured by Yu-Hwa. He kills all of them and concludes that he needs to absorb Yu-Hwa's powers before he encounters more Atran anothers.
Sa-Ryun arrives at the run-down cafe to meet Yu-Hwa but finds Un with him. He overhears Un explaining how Hon is in trouble from Atran as Yu-Hwa and Sa-Ryun is related. So, Yu-Hwa is being used as a bait to draw out Sa-Ryun. Yu-Hwa reveals he has been loitering from properly fixing up his cafe to keep Sa-Ryun from approaching him. Just then, Lecter arrives and comments that Hon is of no use. He takes down Un with no trouble and attacks Yu-Hwa. Sa-Ryun steps in and fights Lecter. From their conversation, it is revealed that Sa-Ryun has killed the heir of Atran and so have been fleeing. That encounter has weakened him reasonably and so Sa-Ryun is gradually outmatched by Lecter. Seeing Sa-Ryun losing, Yu-Hwa thinks of hitting his hyung in order to heal his injuries. Although surprised when hit, Sa-Ryun regains enough power to kill Lecter. A power crystal is emits from the dead Lecter but before Sa-Ryun can take it, Mase arrives to face him. The two fight each other (quite evenly matched) over the crystal which happens to fall right on Yu-Hwa's head and is absorbed by him. Sa-Ryun is shocked at first but takes it optimistically that Yu-Hwa might get enough power to defend himself from now on. Before departing, he tips off Mase on Atran's plan to attack Hon to take the key to pandora's box - Su-Jin Ji.
Sa-Ryun's predictions come true and Hon is attacked by Atran force. Sa-Ryun keeps a distant watch on Yu-Hwa who fightsTar on the way of escorting Su-Jin Ji to evacuation facility. When Jacra and Tar are leaving from Hon premises, he meets them; revealing he and Jacra know each other quite well. They discuss on their interest in Yu-Hwa and Sa-Ryun discloses that Yu-Hwa calls him 'hyung'. Jacra is amused to learn Sa-Ryun growing interest in a human and decides to postpone fighting him. They leave and Sa-Ryun gets his hands on a fleeing prey - Guight, who has just fought Ye-Rin.
Later he is shown leaning on a wall at the rooftop of the building opposite to Yu-Hwa's cafe (refixed with Mase's personal funding). After enjoying the view of Yu-Hwa returning from hospital hale and hearty and having a good time with his friends, he leaves with a sigh of relief.
Sa-Ryun is shown to be very powerful. Later it is revealed that he is a highly dangerous type Another who is entitled as Hunter (one who is adept at killing anyone). He easily defeats the Another who was attacking Han Yu-Hwa.
Sphere: He can create light orbs of various colors with varying effect. They are created out of his powers and are called Sa-Ryun's Spheres. He can also give a limited amount of this orb to someone else to use.
Red Sphere: Shoots aura/power beam to pierce the target.
Yellow Sphere: Enhances the durability of surrounding object. 
Pyrokinesis: He can also control fire  where he only uses a flick of his hand to burn his opponents down to ashes.
Ability Absorption: He can absorb ability of another by killing their owner  and imbibing the power orb.