Recent increases and diversification in illicit drug abuse have raised significant social concerns in South Korea. This study analyzed 31,451 confirmed illicit drug substances detected in seized materials examined by the National Forensic Service in 2025. Traditional illicit drugs, including methamphetamine (MA), cannabis, and opium poppy, accounted for 48.60%, 7.96%, and 9.52% of the total cases, respectively, with MA consolidating its position as the most prevalent illicit drug in South Korea. Among the new psychoactive substances (NPS), synthetic cannabinoids maintained the second-largest proportion at 15.56%, demonstrating a plateaued trend. Furthermore, dissociative drugs such as ketamine and phencyclidine (PCP) analogs continued their upward trend, representing 10.46% and 1.29% of the cases, respectively. Due to the structural and pharmacological similarities between ketamine and PCP analogs, the recent surge in ketamine abuse has driven a parallel increase in the prevalence of novel PCP analogs. This specific class poses a critical challenge of rapid structural diversification, as evidenced by the discovery of 5 novel PCPs, such as 2-fluoro-2-oxo-PCiP. Ultimately. the severe threat posed by these newly emerging PCP analogs and other novel NPS dictates an urgent need for swift and proactive countermeasures.