Three Pranksters

The Three Pranksters (悪巧み三人衆), also known as the Three Leaders (三首領), refers to Rimuru Tempest, Elmesia El Ru Sarion, and Gard Mjöllmile.

Background
At first the three members were simply drinking buddies, but eventually their drunk discussions turned into leaking national secrets. During one of their drinking sessions they came up with the foundation for the Three Wise Drunks.