When Does Rimuru Summon the Primordial Trio in Season 4?
If you’ve been following That Time I Got Reincarnated as a Slime closely like I have, then you already know Season 4 isn’t just another continuation — it’s a turning point. With the official return set for April 3, 2026, and a massive 60-episode run planned, this is shaping up to be the most ambitious arc in Tensura history.
And yes — this is the season where we finally meet the long-awaited Primordial Demoness Trio: Testarossa, Carrera, and Ultima.
As a long-time fan of That Time I Got Reincarnated as a Slime, I honestly think this is the moment where Rimuru stops being underestimated forever.
When Does Rimuru Summon the Primordial Trio in Season 4?
Let’s talk timing.
The recruitment of the Demoness Trio happens during Light Novel Volume 11. Based on previous anime pacing and the confirmed extended format of Season 4 (five cours, around 60 episodes), we can make a very solid prediction.
Here’s my personal estimate:
- Late Cour 1 or Early Cour 2
- Roughly one-third into Season 4
- Likely between Episodes 10–18
If the adaptation keeps its usual rhythm of about three light novel volumes per major arc, then Volume 11 material shouldn’t take too long to reach — especially with the expanded episode count.
Unlike previous seasons that had to compress political negotiations and world-building, this longer format gives the story breathing room. That means the introduction of the Primordials won’t feel rushed — and trust me, they deserve a proper entrance.
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Who Are the Demoness Trio?
By now, anime-only fans already know Diablo (Noir) and Guy Crimson (Rouge), two of the most terrifying forces in the series. But the Demoness Trio completes the Primordial lineup serving Rimuru and elevates Tempest to another level entirely.
| Name | Primordial Title | Color | Role in Tempest |
|---|---|---|---|
| Testarossa | Blanc | White | Diplomat & strategist |
| Carrera | Jaune | Yellow | Heavy artillery / destructive magic |
| Ultima | Violet | Purple | Intelligence & covert operations |
Testarossa is elegance wrapped around cruelty. She’s calm, refined, but absolutely merciless when necessary. Watching her handle diplomacy will be terrifying in the best way possible.
Carrera is chaos incarnate. If you thought Megiddo was scary, wait until you see what nuclear-tier magic looks like when she uses it.
Ultima might look playful, but she’s arguably the most unsettling of the three. Her intelligence work for Tempest adds a darker layer to the political landscape.
How Does the Recruitment Actually Happen?
Here’s the twist that makes this arc so satisfying: Rimuru doesn’t summon them directly at first.
It’s Diablo who takes initiative.
To better serve Rimuru personally, Diablo decides he needs capable subordinates to handle the Black Numbers and administrative burdens. So what does he do? He goes to the Demon Realm and “persuades” three fellow Primordials to serve his master.
When they arrive in Tempest, they don’t bow immediately. They come to judge Rimuru.
That’s what makes this moment so powerful. It’s not blind loyalty. It’s a test of worth.
Once Rimuru names them and grants them physical bodies, everything changes. They become fiercely loyal — not out of fear, but conviction. And from that moment, the balance of power in the world tilts dramatically.
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Why Season 4 Is a Game Changer for Tensura
Let’s be honest: Rimuru has been strong for a while. But with Diablo, Testarossa, Carrera, and Ultima under his command, he controls four out of seven Primordials.
- Diablo
- Testarossa
- Carrera
- Ultima
That is not normal. That is not balanced. That is terrifying.
Politically and militarily, this elevates the Jura-Tempest Federation beyond almost every nation and Demon Lord faction combined. The world will have no choice but to take Rimuru seriously.
Season 4 isn’t just about flashy fights. It’s about power consolidation. It’s about Rimuru becoming a true global superpower.
And honestly? I’m here for it.
Will the Anime Do Them Justice?
The manga, currently adapting these events around Chapter 119 and beyond, is already showing Diablo beginning his recruitment journey. The light novel version gives each of the Demonesses distinct personalities and terrifying presence.
If the anime nails their first appearance, the tension of them judging Rimuru, and the naming ceremony, then Season 4 could easily become the best arc in the series so far.
The expanded 60-episode format gives hope that their introduction won’t be rushed like some past arcs felt.
Final Thoughts – As a Fan
I’ve watched Tensura grow from a fun isekai experiment into one of the most politically layered fantasy series in modern anime. But the arrival of the Primordial Trio is the moment Rimuru’s empire becomes undeniable.
April 3, 2026 can’t come fast enough.
If you’re anime-only, buckle up. If you’re a light novel reader, you already know what kind of storm is coming.
Season 4 isn’t just another season. It’s the rise of Tempest as an unstoppable force.
