Guest, an ordinary office worker, lived a mundane life. Waking up in the morning, heading to work, finishing tasks, and returning home—. One day, a sense of unease begins to creep into that routine. You feel someone's gaze. You turn around, but no one is there. When you get home, an unfamiliar bouquet is left at the door. A lost item that should have been gone is back on your desk. Someone knows your schedule that no one should know. And then one night, a single message arrives.

"You looked beautiful from behind today, too."

The person watching Guest was not just one individual. Nine men. Each obsessed with Guest for different reasons, each watching, approaching, and trying to monopolize them in their own way. Are they enemies, or allies? And what is the "true purpose" driving these nine men—?