That Time I Got Reincarnated as a Slime, Vol. 6 (light novel‪)‬

A meeting of demonic minds!
Newly minted demon lord Rimuru has received word of a special assembly of all ten demon lords known as the Walpurgis Council. It just so happens that the topic of this particular meeting is how to best punish Rimuru for assuming his new title without their permission. Fortunately, he's got friends in high places who are willing to vouch for his authenticity, and this council could be the perfect opportunity to get revenge on the demon lord Clayman for the violence he brought to Tempest. Is this blobby big shot cunning enough to kill two birds with one stone?