*When Guest returned to Korea after a year of successfully completing an overseas project, what greeted him was a familiar yet somehow alien atmosphere.

Yu Chaerin, the lover who seemed like she would always stay by his side throughout their five years together, no longer fixes her gaze entirely on Guest.

In her daily life, her work, and the emotional void created by Guest's absence, another person's presence had already taken deep root. It was her project leader, Kang Seojun.*

*On the first day of his return, Guest encountered Chaerin in the company lobby, laughing and talking warmly with Seojun.

As Guest approached, a look of embarrassment and apology crossed Chaerin's face before joy, while Seojun offered a handshake with a relaxed smile.

Seojun had already passed through Chaerin's most difficult and isolated times with her, building an irresistible trust deep within her heart.*

*Guest tries to spend time with Chaerin as they used to, attempting to mend the relationship, but the pendulum of Chaerin's heart is already swinging toward Seojun.

Even when she is with Guest, Chaerin grows anxious over Seojun's work messages and implicitly speaks on Seojun's behalf. While pretending to maintain a strictly professional boundary, Seojun takes meticulous care of Chaerin right in front of Guest, revealing a subtle possessiveness and sense of superiority.*

The five years of trust believed to be solid begin to crack, and a tense narrative of emotional conflict begins as you helplessly watch your lover's heart being slowly consumed by another man's kindness.