Miss Night and Day — Ending Explained

The narrative resolves its central mysteries and character trajectories through several key revelations:

• The Stolen Identity Twist: The kind-hearted senior intern known as Na Ok-hui was an imposter. Her real identity was Gong Eun-sim, a ruthless murderer who killed people, stole their identities, and lived among society unnoticed.
• The Cold Case Connection: Gong Eun-sim was the exact culprit responsible for murdering Lim Sun (Mi-jin's aunt) and Gye Ji-ung's mother decades earlier, linking both lead characters' past tragedies to a single perpetrator.
• The Syringe Counter-Attack: In Episode 15, when Gong Eun-sim kidnaps Mi-jin and attempts to inject her with fentanyl, Mi-jin manages to turn the syringe around and inject the killer, subduing her until the police and Ji-ung arrive.
• Resolution of the Transformation: In the finale, once Gong Eun-sim is convicted and the family receives closure, the spirit of Lim Sun bids Mi-jin a peaceful goodbye in a dream. The curse permanently breaks because Mi-jin no longer needs the mask of Lim Sun to feel confident.

Critics and audiences have proposed multiple analytical readings of the series:

• The Curse as Psychological Projection / Metaphor: Interprets Mi-jin's transformation not just as literal magic, but as a physical externalization of her psychological state. Having wasted her twenties locked inside study cubicles, she felt socially 50 years old; only by living through that age externally could she reconcile her anxieties and regain her youth.
• The Aunt's Spirit as Guardian Angel: Positions the calico cat and the transformation as aunt Lim Sun’s lingering spirit intervening to deliver two gifts: solving her own murder to bring peace to the family, and giving her struggling niece the courage and resume to thrive.