Diablo

Diablo is the named Archdemon faithful servant of Rimuru Tempest. After being named, he has evolved into a Demon Duke and is currently one of the most powerful people in Tempest.

Appearance
As an Archdemon he was a beauty whose gender was indeterminable. He have deep crimson hair.

Personality
As a named monster of Rimuru, he is extremely loyal to his master and summoner. When two of his subordinates were sacrificed to fuel Rimuru's revival spell, he felt envious that they could be of use to his master. His aim is to be Rimuru's right hand man.

Birth of a Demon Lord Arc
By offering the corpses of the Blood Shadows and the 15000 human soldiers, Rimuru summoned an Archdemon and his two greater demon subordinates. Using the corpses they were successfully able to materialize. He ordered them to capture the the three escaping Blood Shadows, and bring them to Ranga.

The secret revival art was lacking the necessary energy. so the Archdemon offered his two subordinates. They were delighted to be of use to Rimuru. Hence, when Rimuru awaked he was grateful and allowed the Archdemon to become one of his comrades. When Rimuru found out he didn’t have a name he named him Diablo. And told him to become his guardian deity. A black cocoon enveloped his body creating a perfect evolution posture.

Saint Demon Confrontation Arc
It is later revealed that he is in fact not a Archdemon, but a Demon Duke. "I am not an Arch demon like you had previously said, but a Demon Duke." He reveals while battling a Templar Knight. A Demon Duke is a legendary existence. It is supposedly ranked higher than a self-proclaimed Demon Lord. There has been no other Demon Duke summonings previously documented.

Black Corps
He is founder and a leader of Black corps The Black Number: 700 personnel consisting Old rivals and their subordinates and unique individuals

These are the names of the Arch demon trio:

Testarossa

Ultima

Carrera

Simultaneously as they are named, the incarnation and evolution process has completed, they leave their capsules as demon dukes and all three of them, are beauties.Their might is horrifyingly overwhelming, their strength is on a completely different dimension.

The greater demons names:

Venom

Veyron

Moss

Shien

Zonda

Agera

Esprit

Naturally, their evolution had also completed in an instant, and emerged from their cultivation capsule They have the strength of Arc Demons.

The souls of our subordinates who are not present here, If you may please permit them, access to these dolls

the souls of lesser demons are just right for inhabiting the demon dolls.

They’re only going to have the strengths of greater demons, but that’s not a problem.

Since it’s going to take a lot of magical energy, anything beyond this seems impossible, but it’s probably alright.

Dozens of Greater demons with abilities above A ranksIf there’s someone among the weak with a unique ability, they might even evolve into a strong Arc demon.

It seems like the number of subordinates there are 100 Greater Demons.

and a total of 700 lesser demon souls are lodged onto cultivated demon

After this, the demons that came out of this revealed to be great

With abilities that surpass Majins, they’re all terrifying great demons.

As I’ve expected, the summoned high-ranking individuals are stronger than a newborn arc demon.

They’ve become an unimaginable corp.

Magic

 * Magic Energy Manipulation Archive
 * High Demon Summoning

Unique Skills

 * Great Wiseman: Thought Acceleration, Thought Domination, Incantation Void.
 * Tempter: Fascination, Seduction.

Extra Skills

 * Multiple Barriers
 * Spatial Travel

Daily Skills

 * Magic Perception
 * Demon Lord’s Ambition

Battle Skills

 * Law Manipulation

Resistances

 * Physical Attack Nullification
 * Natural Effect Nullification
 * Status Change Nullification
 * Spirit Attack Resistance
 * Holy Magic Attack Resistancel

Relationships

 * Rimuru Tempest: He is truly loyal to Rimuru, and will spread calamity if ordered.

Trivia

 * He have red hair color in the Web Novel and black in the Light Novel.