Here's the real reason why the author of That Time I Got Reincarnated as a Slime was inspired to draw Rimuru as someone cool ...

allowing them to witness the true evil of the Kingdom of Falmuth, and then proclaiming himself as a loyal follower of Rimuru Tempest, a monster that wants to ally with humans, worked much more.

Rimuru's moves offer a decent amount of damage that will come in handy when dealing with enemies. You need to collect 5 Tempest Ore to unlock this spec.

In episode 5, after Falmuth's Archbishop Reyheim gives his account of what happened on the battlefield during the intended invasion of Tempest ... of Demon Lord Rimuru and the Evil Dragon ...

A long-running conspiracy is swirling over a mysterious power wielded by the Queen in Raja, a small country west of Tempest. When a slime who evolved into a Demon Lord named Rimuru Tempest crosses ...