Mipherius

Mipherius (ミフェリアス) is an original character created for That Time I Got Reincarnated as a Slime: Isekai Memories x KonoSuba collab. He was made from the restless souls of Otherworlders from Central World and Kazuma's world who died in their Summonings or were killed after being Summoned here.

Appearance
He resembles a phantom like creature with red eyes.

In his Charybdis Toad form he resembles Charybdis except Green and with some frog traits due to taking on Giant Toads from Kazuma's World.

Personality
He feels envious of Rimuru for building a nation and Kazuma for having a harem due to the spirits influencing him as they felt lucky while the restless souls making up him was very envious of Rimuru and Kazuma being lucky since they died during their summons or died after being summoned.

He also seem to hate those with "cheats" such as him complaining when Rimuru used a Anti-Magic Barrier to stop him from bending reality to evade his attacks.

History
He was created from the restless souls of Otherworlders who died from failed Summons or were killed after being Summoned in Rimuru and Kazuma's worlds.

In Kazuma's world he attempted to destroy Kazuma's party but Megumin's Explosion Spell blows him away and transported everyone to the Central World.

In Tempest he attempts to manipulate Gabiru into all fight with Kazuma until Rimuru broke up the fight. He also attempted to Summon in monsters from Kazuma's world to attack Tempest.

He would reveal himself in attempt to destroy Rimuru and Kazuma's party but is defeated by Rimuru. However in a last ditch effort he transforms into a Charybdis Toad and attempted to destroy Tempest. However Rimuruh the help of Megumin combines a explosion spell together that finally ends him once and for all.

Abilities
He is able to open portals between worlds as he brought Kazuma's Party to the Central World and summon in monsters from Kazuma's world to do his bidding. He also alter reality to some extent dodging Rimuru's attack until he placed a Anti-Magic Barrier around him.

In his Charybdis Toad form he has the abilities of Charybdis and Giant Toads from Kazuma's world and the only way to damage him if he is attacked by two attacks one from Rimuru's world and one from Kazuma's world as Rimuru and Megumin used a combined explosion spell to end him.

Trivia

 * Mipherius was the second entity that Rimuru teamed up with another series character to defeat that he couldn't beat on his own after Lilia of Desire from the Seven Deadly Sins series in Seven Deadly Sins: Grand x TenSura Collab with the help of the Seven Deadly Sins.