What makes Act. 1: The Little Mermaid by Gugudan notable?

'Act. 1: The Little Mermaid' not only showcased Gugudan's unique concept but also reached significant commercial success, charting in South Korea and solidifying their presence in K-pop. The album received positive reviews for its thematic coherence and musical diversity, contributing to the growing popularity of girl groups within the genre. Released on June 28, 2016, 'Act. 1: The Little Mermaid' marks Gugudan's debut mini-album, introducing the group to the K-pop scene. At this point, Gugudan was freshly formed from the survival show 'Produce 101', positioning them as a new contender in a highly competitive industry.