When Rimuru named Testarossa, Carrera, Ultima, and the hundreds of demons that accompanied them, many readers wondered how he managed to survive. Earlier in the series, naming only a handful of powerful monsters was enough to leave Rimuru unconscious for days. Yet this time, he successfully named three Primordials and their entire force without dying.
The answer lies in how much Rimuru had changed since becoming a True Demon Lord.
Rimuru Had Become a True Demon Lord
By the time Diablo recruited the Demoness Trio, Rimuru was no longer the same slime who struggled after naming the ogres. His Harvest Festival had transformed him into a True Demon Lord, dramatically increasing both his magicule reserves and his overall capabilities. He had also acquired the Ultimate Skill Raphael, which could precisely calculate and manage the enormous amount of energy required for naming.
Even then, the process was far from easy.
Naming a Primordial Demon required an unbelievable amount of magicules because they were already among the strongest beings in existence. Naming three of them back-to-back, along with their elite subordinates, would normally have been impossible for almost anyone else.
Fortunately, Rimuru had prepared for this without even realizing it.
Raphael drew upon the massive stockpile of magicules Rimuru had accumulated over time, including reserves stored within his body. The specially prepared incubation capsules used for the Primordials’ vessels were also filled with magicules, further reducing the burden during the naming process. Although Rimuru nearly exhausted his reserves and even reverted to his slime form afterward, he survived because Raphael managed the entire process with perfect efficiency.
Why the Demoness Trio Needed Special Vessels
Unlike ordinary demons, Primordials are spiritual lifeforms. They cannot simply remain in the Cardinal World indefinitely without an appropriate physical form.
For that reason, Rimuru prepared high-grade artificial bodies for Testarossa, Carrera, and Ultima before naming them.
These vessels were not ordinary human bodies. They were specially engineered to withstand the immense power of Primordial Demons while allowing them to remain permanently in the physical world. Without suitable vessels, their manifestation would have been unstable, and they would have eventually been forced back into the Demon Realm.
The vessels essentially served as perfect containers capable of housing beings whose power far exceeded that of ordinary incarnated demons.
Why Diablo Didn’t Need One
Diablo’s situation was completely different.
When Rimuru summoned a Greater Demon after the Falmuth massacre, Diablo deliberately answered the summoning instead of allowing another demon to appear. Because he entered the Cardinal World through a proper summoning ritual, the summoning itself allowed him to manifest with a physical body.
More importantly, the ritual included an enormous sacrifice.
The bodies of the fallen Falmuth soldiers were offered as part of the summoning, providing Diablo with an exceptionally durable vessel capable of permanently supporting his existence in the physical world.
In contrast, Testarossa, Carrera, and Ultima were not summoned by Rimuru.
Diablo personally recruited them in the Demon Realm and brought them back to Tempest. Since they entered the Cardinal World without going through a summoning ritual, they had no physical bodies waiting for them. Rimuru therefore had to create suitable vessels before they could properly incarnate.
The Difference Between Diablo’s Body and the Trio’s
Although both Diablo and the Demoness Trio ultimately received permanent physical bodies, the way they obtained them was completely different.
Diablo’s body came directly from the summoning ritual itself. The sacrifice of thousands of corpses allowed him to materialize with a vessel powerful enough to contain a Primordial Demon immediately.
The Demoness Trio, however, arrived as spiritual beings without bodies. Rimuru solved this by creating specialized artificial vessels specifically designed for Primordials before naming them.
In other words, Diablo’s body was a product of summoning, while Testarossa, Carrera, and Ultima relied on engineered vessels prepared by Rimuru.
Final Thoughts
The entire event demonstrated just how far Rimuru had evolved.
Not only did he successfully recruit three Primordials—something that shocked even Guy Crimson—but he also possessed enough magicules, planning, and support from Raphael to provide them with permanent bodies, name them, and even name their army.
For most beings in the world, naming a single Primordial would have been suicidal.
Rimuru managed to name four of them, establish the Black Numbers, and survive the process—proving that he had reached a level where even the ancient rules governing monsters and demons no longer applied to him.
