Rimuru and friends visit Celestial Emperor Hermesia's resort island after the Jura-Tempest Federations opening ceremony. During their vacation, they encounter a mysterious woman, leading to a new incident by the azure sea.
When a popular MMORPG is scheduled to be shut down permanently, veteran player Momonga refuses to log out. As NPCs begin to develop personalities and minds of their own he decides to put his skills to use as the game's new overlord.
