Diablo vs. Guy Crimson: The Long-Awaited Reunion Shakes the Demon World
- animefocusnetwork
- Mar 4
- 4 min read
Updated: Mar 6
Published on March 4, 2026
Chapter 139 of That Time I Got Reincarnated as a Slime changes everything! This was one of the most hyped chapters to date, with an unexpected foe entering the battlefield. Diablo, as always, is one of my favorite generals of Rimuru -- there's a knightly charm to him that makes you feel that he has everything figured out.
This new chapter brings one of the most awaited moments since Guy was first introduced to Rimuru during Walpurgis (where demons meet up). During this meeting, Guy Crimson wondered why Diablo was serving Rimuru, and now we finally know why!
What Led Up to Diablo and Guy Meeting
During Chapter 138, Diablo was about to face off with a powerful insectoid, who is one of the greatest rivals of demons. However, Diablo said to Rimuru, "I have one other concern," which led to Rimuru telling Diablo to go deal with it.
This is when things really got heated, and it felt like one of those big moments, I just knew something huge was coming. Out on the field stood Bleu, who is now known as Rain the Primordial Blue, under Guy Crimson, who is said to be the strongest primordial of them all. However when Diablo fought him, it ended in a draw, so personally I think Diablo is the strongest, but that's just my personal opinion.
The battle was completely one-sided, with Diablo utterly demolishing Rain. He fully intended to kill her, but then paused and realized that Rimuru expected him to leave the insectoid to Shion and Ranga instead. Out of boredom he decided to keep her alive and stall if you will. In the end, this brief clash concluded with Diablo casually asking Rain to arrange a meeting with Guy Crimson
Guy Crimson Meets Diablo
One of the most epic scenes in the series just happened, and this gave me goosebumps (no lie). We finally see Diablo and Guy Crimson meet, and things take a turn for the best.
Diablo reveals to Guy that not only did he join Rimuru, but the other 3 Primordials as well: Blanc (now known as Testarossa), Violet (now known as Ultima), and Jaune (now known as Carrera). This left Guy with a shocked expression, because not only does Diablo fall under Rimuru, but 3 other primordials as well.
This completely changes the balance of power, basically putting Rimuru at the top, besides the True Dragons which Guy Crimson refers to as "a phenomenon." This does not mean Rimuru is stronger than Guy (well, not yet), but it means he is gathering a lot of strong allies, which would put him at the top.
During this meeting Diablo also confesses that Rimuru gave him a change of heart, because before meeting him, he did not want to attain any new level, because he thought he was strong already. Diablo stated, "I fear that if I do not make an effort of my own, even I might be left in the dust. And in that sort of environment, there is no longer any reason to set limits on my growth."
Diablo basically just admitted that Rimuru will become the strongest there is and following him will make him strong as well. Although he does not mean this in a way that he will become stronger, rather he wants to follow someone who is strong and serve them. In this way he is choosing to continue evolving alongside his master.
A Future Meeting Will Take Place
Naming 3 primordials isn't any feat a normal demon lord can pull off. Guy says, "He could have easily died or been wiped out of existence for good." This very thought made Guy even more interested in Rimuru. He said to Diablo, "I think I'm gonna need to talk to him directly. I better pay a visit to Rimuru before too long." Diablo says that he would be most welcome. This is due to the fact that Diablo thinks Guy is visiting Rimuru simply to find out more about Diablo's intentions. This wrapped up their conversation, and oh man, this scene was crazy good. I highly recommend reading at least this part!
Editor's Thoughts
This chapter kept me engaged, and unlike other newer chapters (a lot of talking), I was very deeply connected to it from beginning to end. There's something about Diablo that just makes you want to watch/read about him all day. That knightly honor and ever-dying loyalty to Rimuru portrays him as a knight (well, sort of) keeps him fresh and mysterious.
This was truly one of the best moments since Rimuru's battle against Hinata. This scene not only has politics in it (widely) but lore that pushes the story further in the direction that leads to more powerful beings entering the story. Not only that, the battle against Rain was short, but it was done in a way that showcases Diablo's power even more. — Dean
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