Summary
Gi-yul has liked Seomoon for years, but their relationship has been “just friends” until now. A professional opportunity arises: Gi-yul is filming a mature-themed music video (or shoot) that requires a sensual / intimate atmosphere. To “set the mood” for the shoot, Gi-yul attempts to use a sex toy (i.e. for self-pleasure, presumably to get himself in the right headspace / feeling). Seomoon catches him in the act (Gi-yul being intimate with himself / the toy). Instead of reacting with embarrassment or avoidance, Seomoon offers to help.
From there, the story moves into an emotionally charged, steamy scene where feelings long suppressed / unspoken between them come to the surface. Surprise, attraction, perhaps affection, maybe guilt or tension. Gi-yul’s long‑crush dynamics come into play.