The other's discovered that Iruma wasn't actually a demon so they secretly helped in what lead to his death by staging their reactions, and even planning their positions and group pairings to solve extent. What none of them or even Makai as a whole became aware of later was that after his death, Iruma reincarnated as the individual named Rimuru Tempest (things go cannon with the only difference being that Veldora isn't Rimuru's first friend since the misfits - who he figured out to be involved in his death - betrayed him).
Veldora became his first true friend however and learned of Rimuru's past since Rimuru still wanted to have someone who knew him, whom he could fully trust with his troubles. And who better than a tsundere dragon like his all but blood brother Veldora who was like family to him? Who he met at the start and had been with ever since? After everything was said and done (Walpurgis ended peacefully according to the manga), Rimuru, during a Walpurgis LONG after the Clayman case (3-4 years later) suddenly was the target of spacial interference. Magically intangible glowing cubes surrounded him, circling with a blue and yellow shade to them. '!??'
He awoke startled from his position as Raphael -yes he had basically dozed off-, (Author: I like Raphael more than Ciel, but pardon if she sounds a bit like Ciel. I don't read the novel but some writers write her like a control freak so... nah.) reported the situation to him. The other 7 demon Lords and those who came with them were surprised when one of them was getting pulled elsewhere. Intrigued by what was going to happen some of them 'jumped on the cart' and went with him for their probable later amusement. Additionally, Rimuru's patrons also went along since they had rushed to their startled lord when he was gave notion of getting, well, surprised. Though not all of them could come along since they all held obligations to their home and their Lords land. In short the ones who went along were:
From Tempest; Veldora who couldn't leave his all but brother alone, the Oni's, Gobuta (?, Why's he there?), Gabiru who thought himself obliged to come, Ranga and the Ninetails who had been named Kumera and had gained a human form for quite some time now. (This might be AU as I don't read the novel and am only partial to YouTube, Manga, and some other stories on Wattpad v*>*v)
The rest consisted of most of the remaining 8 star demon Lords (Ramiris, Milim, Crimson Guy, Valentine, Dino and an interested Leon Cromwell) as well as the ex-Maou's Frey and Carrion. Wrath of the giants passed, he preferred to be told later, should one of them wish to elaborate on their little 'field trip'. He made himself comfortable; well, one of them should probably stay back incase something happens.
So they all let themselves get swallowed by the swamplike transport entrence, their fall being like that famous hole from Gravity Falls - dark with a light at the bottom that never stood to get bigger. Until I suddenly did.
As if the fabric around them was spewing out water, so did they arrive in the new environment... with some space between them thankfully. Everyone had skills and resistances that helped them in such travels, so they not only maintain their dignity but could also get out of the shaky transmigration unharmed enough to scan their strange newfound surroundings. As most of them had high level skills they also noticed that said abilities had remained untouched - some of them used Spatial detection or observation.
"This is a place I've never been to before.. Interesting" Guy looked around their 15-20(?) group with a seemingly merry attitude. Ladies like Valentine didn't share his nice sentiment or outview, "This place doesn't seem like it's of much importance to me, it's barren and barbaric.. I doubt that anyone who lives here could be useful to us."
Dino was just lying on the floor... The very hot floor that he could lean or sleep on, he looked more sour than usual... If he was sour at all, or was that just him being sleep deprived?
Milim was approached by her subordinates, the two ex-demon Lords Frey and Carrion as they discussed and inspected their new surroundings, Milim was lively marveling at it all. After all, she's one of the oldest demon Kings their world had to offer, she had seen their world for more than a thousand years minimum, so this was all very interesting for someone like the childish dragon princess. Frey had no problem with that, she just made sure to not let Millim out of her sights lest they lost her. Carrion on the other hand wasn't liking the places living conditions very much...
The Tempest inhabitants gathered together as they went to their lord, they wanted to greet him but no reply was given. Benimaru who was the first to gaze upon Rimuru was a blank face... Except that his golden eyes were widened in what seemed to be disbelief and or shock even, he was sitting on his butt holding his head when both hands; knees drawn close. His current reaction was still exactly the same - if not slightly more stressed - than what called them into following Rimuru through the inter-dimensional teleport. They weren't the only ones to take notice of this, however, their attention was directed elsewhere as soon as what looked to be security personal approached them from the air.
It was a total of what seemed to be three demons, looking almost identical to Diablo... Rimuru had quickly taken his mask out when the attention was taken off of him. At the top of the trio was a man with red hair tied into two ponytails that ended with a bit curl. He was also wearing glasses and had a suit on much like the ones behind him, though their power was different.. It was weak compared to them.
"You. What are-"
"Umm? Who might you be?"
Ameri's dad (Henri I believe) was in the middle of talking when Guy interrupted him...much to the old demons chagrin. The other redhead however compromised to some extent by taking out his police badge, same with the other two officers behind him. "Azazel Henri, I am in charge of safety and security of the demon world. Who are you to be standing so close to the castle? Are you invited nobles? I've never seen you before?"
Since Guy looked like he got in the mood to prank or bully the man that was just doing his job, he was bushed aside by his draconic partner Velzard and Valentine.
"We were just taking a stroll around before going to the party, is that such a bad thing to do? Since we're such a big group and some of our members are exhausted from a race they had we've just been taking our time" Valentine lied flawlessly, Velzard finishing the conversation just as perfect making Velgrynd sigh at her sisters drama play, "Do you think we're weak enough to be looked down upon? Any of us? I'm sure you will be more attentive next time".
Henri had to indeed retreat, there was a feeling of dread coming from the group. They made his heart almost stop, 'I don't need a scare on Sullivan-sama's level, no, not again'. He was an ex-crown but how was he feeling dread from these no-names!?
Henry gave a light bow, the two behind him bidding farewell by pulling their caps down, "Well then.. Excuse my ignorance, I hope I'll see you at the ceremony and congratulation party". They took off to somewhere lower, looking over there was a castle with atleast 200 stories in it. They were amazed at the sight, 'Its like Rimuru's labyrinth was heaved up into plain sight like a tower'.
Waving through her hair Velzard looked at everyone, "I propose that we calm down and enjoy some food while we discuss how to get back and what this place is".
Everyone nodded, Rimuru had stepped closer to Veldora almost clinging to him like a child. He of course saw this as a cute gesture he normally only gets when they are alone, so he'd think about this later. Those with wings flew like the demons, which wasn't hard for the majority who had dragon, bat, bird or whatever type of wings. The rest used the shadows or fancily jumped over/teleported.
.
.
.
So they had appeared just outside the demon Kings castle.. were a ball was held to congratulate the newest member of the 13 crowns and the crowning of their demon king huh.. Neat. The 13 crabs or whatever consisted mostly or basically of some of Iruma's former classmates. The new Maou was the grandchild of one of the three 9th ranks... Whatever that meant. It was still an interesting piece of information, the social ones amongst them quickly went around for more rumours; Ramiris was quite the odd sight for the demons partaking in the event. As for Rimuru, he became a wall flower; Veldora chose to sit with him on a sofa after getting some plates with great amounts of food on them from Daggruel who also didn't want to do anything.
Among the ones attending, Rimuru - Iruma - recognized a few high class figures like Calego and Ballam-sensei, who were also there standing close with some of the former crowns.
"So you know them?" Leon turned his eyes down to Rimuru, who was in the middle of putting down his mask making them see his rather disgruntled looking face as he looked at the waltz dancers.
"Yes..I know them, most of them. I know this place but...I don't know the exact location of it from our dimension. It will take some time till I figure out the way back... I'm..sorry.. Very sorry."
The members of Tempest stood shocked as they heard their dear Lord apologize; its rare to hear him apologize as usually there's no reason for him to do so! - He's normally so calm and observing that he moves without errors. Even then he is the idol they all admire with all their hearts!
The other demons and Demon Lords of their world however, were rather focused on his words and expression, he seems very uncomfortable being here. Rather, it sounded like he was apologizing to himself and not them.. 'He seems to have a history here..' they concluded looking around more.
Now Veldora was the one most considered closest to Rimuru; he's heard of his past, has seen the actions he's taken..concluding some short ends with his ultimate skill.. and he knows his brother good enough to know they WILL be together in the far future as well. Which is why, he knows that there are only 3 'places' that could make his little bro this... shaken.
1st was the home of his 2nd life's (Iruma's) parents. -> Neither those whom they had encountered so far nor this place fitted anything considered human so no.
2nd was the demon school he had attended and died at -> Demons? Sure, but there was no school in sight. However, the demons right now may just be the same inhabitants judging from their weak aura and limited skills.
3rd: His first life's world altogether. Though, he would be shaken in a different kind of emotion and not this. Also how or why would that 'normal and without magic' world seek out a demon lord from their world? No..
All in all, the option which made the most sense was...
"This is 'Makai' isn't it Rimuru?". Veldora, whose sisters have never seen him look so grim and serious, put a hand on Rimuru's knees as he went to kneel before his little brother and looked at his sad face. Guy Crimson had stepped forward tilting his head in ridicule but also holding small well disguised interest, "Makai? Shouldn't that be a foreign name for the demon world? I'm sorry to say this to you Veldora but I've never seen this place before as a primordial."
The other primordials would've been the same, if not for their lack of presence or not wanting to upset Rimuru for personal reasons.
Veldora's eyes glistened back at him darkly, "Just because it doesn't look like how you know it, doesn't mean it couldn't be one, this IS a different dimension after all".
Meanwhile Diablo was like this.
Rimuru later figured out flabbergasted as he did, that the reason for his attendance was that the demon Kings crown - which was fated only for the future demon Kings - had called him forth as it was sat down upon the head of Beelzebuth. He... had been destined as this world's Maou at one point huh.. They hadn't appeared inside the throne room, which led the demons there to firmly believe that they had the right demon for the job. Although saddened and conflicted greatly, Rimuru was able to reunite with his old ring which had refused to have a new owner ever since.. OP Ability what else could be desired?
Although Rimuru now had a skill that caused the same effect and more, he still took the ring of Gluttony with him. Whose spirit and actual identity was happy to see him again and in better hands.
-> former Demon Kings spirit.
-> Rimuru opted to revive him as the 'current' Maou was too young in his eyes to fill out the position and the required tasks. They went into the ball /throne room with the former demon king.