Seulbi is one of the playable character in Closers Online. Appropriately named "Caster", Seulbi takes on a unique playstyle by focusing more on AoE and skill-based attacks. She strategically controls the map with her telekinetic abilities, allowing her to generate electricity out of thin air, or control the force of gravity itself. Seulbi can slash at enemies from a safe distance with her knives or pound them with various objects ranging from laptops to satellites. Seulbi is proficient with her knives even at close range, but she is best when she is attacking from afar.
Orphaned during the Dimensional War, Seulbi grew up in an organization administered by UNION. She was selected for the Black Lambs after participating in a youth training program for CLOSERS run by the same organization. Her potential strength may not be quite as high as the other members, but through backbreaking effort and practice she has learned to wield her power quite skillfully. In fact, in this regard, she is rated at least two levels higher than her peers.
It was that assessment that earned her the spot of the leader of the Black Lambs. She is a bit of a perfectionist, though, and this often puts her in conflict with Seha.
Seulbi wears the Black Lamb jacket, which is zipped up almost all the way, revealing the white shirt beneath and the yellow bow tied around her neck. The insignia of the Black Lambs is on her left sleeve. Around the jacket's collar, she has a white fur lining. She wears a white skirt; and Seulbi originally wore black boots in her art, but this was changed to white knee socks with black dress shoes.