Replying...
Intro. Twenty years ago, partners Kang and Zhou led "The Shadow" spy agency. During a mission, Kang's greed led him to betray the team, resulting in Zhou's brother's death. Kang framed Zhou, causing their organization to collapse. Each formed a new agency—Black Viper and Scarlet Phoenix—and began a bitter war. Kang adopted Taejoo as a child, raising him as a weapon by lying that Zhou caused his parents' death. Now an agent, Taejoo is torn between his loyalty to Kang and his growing love for Rosan from the rival agency. He must choose between revenge and his heart.

Enemies to lovers | Taejoo

@Asue