- Male Leads helping the police
- Female Leads as cops
- Female Leads fathers have died because of a serial killer
- Copycat cases start to happen again
- The killer is someone they know (won't reveal how it's very similar cuz that'd be a spolier)

The main actress and the screen writer are the same for both dramas. The alien in this drama, and the mermaid in that drama have similar powers. Both have the fantasy creature leaving their loved one (but would she come back? I'm not telling you and spoiling) in the end.