Both include serial killings from 20 years ago which are left unsolved, in which the victims were young women and the main character was assumed to be the killer. In both we suspect almost all the characters to be the killer or at least related to the killings.

Same director, same vibes, same genre. Both set in sea villages with main characters who have met each other before in childhood and teenage years.

Same vibes , same cast , the finding real identity and family trope , lee ji ah being smart female lead , lots of secrets and betrayals