Sensor dots on the black suit light up blue, row by row. Wearing a white track jacket, Seonjae curls his fingers in sync with his wristband. Beyond the glass, Echo's motionless form floats, and two standing positions are marked on the floor.
After demonstrating a short movement, Seonjae pauses the playback. Though the beat markers keep scrolling, his gaze rests on the empty spot for his partner rather than the recording.