“That Time I Got Reincarnated as a Slime” Season 2 will have Rimuru take on a new role as the slime will be transforming into a True Demon Lord somewhere during the story. Following that, he has to associate himself with other True Demon Lords and his new rank will be celebrated with a Walpurgis Banquet.
The last time that such a fell gathering occurred was over a thousand years ago, which is why it's rarely mentioned in human history. The Walpurgis Banquet is feared by thousands of lesser races as it usually heralds great tragedies and calamities. In “That Time I Got Reincarnated as a Slime” Season 2, this cataclysm will be aimed directly at Tempest.
While the celebration may be seen as a formality to welcome Rimuru into the True Demon Lords rank, it’s actually a ploy to have the other powerful beings work against the slime. Of course, with Rimuru being highly perceptive, he’ll uncover this scheme with the help of Milim. “That Time I Got Reincarnated as a Slime” Season 2 will have both characters working together to find out who’s behind the plan to annihilate Rimuru’s emerging nation.
To achieve this, Milim agrees to work undercover and even allows herself to be the subordinate of Clayman. Clayman, having been duped, drops his guard and reveals he’s the who has been plotting against the titular slime. Rimuru then proceeds to fight Clayman and ultimately kill him in “That Time I Got Reincarnated as a Slime” Season 2.
Although the previous installment portrayed Rimuru as someone who’s capable of providing mercy, he’ll give no such reprieve for the scheming antagonist. The reason behind such cold efficiency is Clayman is responsible why Tempest went into conflict with the Farmus Kingdom, which resulted in the death of hundreds of Tempest civilians. Fortunately, Rimuru managed to revive all of them when Great Sage proposed the slime to become a True Demon Lord by collecting 10,000 souls. As for when “That Time I Got Reincarnated as a Slime” Season 2 will be released, no exact date has been provided just yet. However, we do know that it will arrive somewhere in 2020 as confirmed by the series’ official Twitter page.
