I am Kamen Rider who reverses dimensions

At this moment, Dr. Romani, located in Chaldea, murmured in surprise after seeing the situation in the Underworld through Fujimaru Ritsuka. Gilgamesh, standing to the side, put down the stone tablet in his hand and said wearily:

“That is the defense mechanism for the living to trespass into the underworld. It is the order established by the world of Uruk, and Tiamat is no exception.”

"That's right, that's right, it's a privilege that's exclusively mine."

Ereshkigal then ran up to the temple, stood beside Gilgamesh, and proudly puffed out her chest, saying:

"Although that place is unusually quiet, I am quite powerful when it comes to actual strength."

"Wait, if that's the case..."

Mashu realized something and said timidly:

"Then, does that mean I, the senior, and the king cannot go to the underworld to fight?"

"...This is not a big problem, as long as I give you protection from the underworld."

After a barely perceptible silence, Ereshkigal readily agreed, but Gilgamesh immediately and ruthlessly exposed her, coldly saying:

"Breaking the taboos of the underworld and granting undeserved blessings to the living? Are you trying to turn the underworld against you and kill yourself? Hmph, what a reckless goddess! Even I can't stand it anymore. Get your priorities straight! In this situation, you can't afford to put on a brave face. Go and focus on dealing with Tiamat. When you can't hold on any longer, then we'll send you all up to die and receive your blessings. Hurry up!"

"What an unlikable King Uruk!"

In the underworld, Ereshkigal, having overheard the reprimand through his avatar, muttered a dissatisfied remark, then brandished his spear and shouted in a deep voice:

"Garula spirits of the underworld, arrayed spears of decay, unleash our underworld's iron hammer upon them!"

As the goddess of the underworld gave her command, crimson lightning transformed into spears, swarming towards the mother goddess Tiamat. The terrifying power caused the goddess to let out a mournful cry of "aaa—". Ereshkigal, however, calmly turned the spears around and said expressionlessly:

"Even Tiamat, the creator goddess, is just an ordinary deity in the Underworld, utterly insignificant under the combined attack of me and the Underworld..."

Ereshkigal's words suddenly paused. She saw the black mud spreading from beneath the Mother Goddess, the Sea of ​​Life, the Chaos Tide, beginning to spread in this underworld. As Ereshkigal was astonished, the surging black mud instantly enveloped the Mother Goddess Tiamat. Meanwhile, on the Chaldean side, Romani, looking at the analysis data on the control panel, hurriedly said:

"This is bad! The Chaos Tide is eroding us, and the Mother Goddess's spiritual foundation is changing. If this continues, the Underworld might be taken away!"

"Eh!!! What, what's going to happen?! Even... even the underworld can be taken away?!"

Ereshkigal clutched her spear in terror, screaming. Though her tone suggested disbelief, she had already sensed the decline of her own power, confirming Chaldea's analysis was correct. However, before Romani could finish speaking, the doctor, watching the data flashing across the projection screen, said in a low voice:

"The Spirit Origin Expansion Project has ceased, the Magic Furnace Core has been confirmed to be continuously restarting, the damage from the fall into the Underworld has been repaired, and the fluid deformation is complete. Everyone be careful, the one standing in the Underworld now is the true Creator God!"

Following Romani's prompting, Tiamat, who reappeared from the black mud, underwent a dramatic transformation. She now possessed a mutated dragon body approximately sixty meters long, with the chest of a mammal, tentacles of a mollusk, scales of a reptile, claws of a feline, and so on. The origins of all species were displayed on her body. This deity, whose spirit origin had returned to the Jurassic period, was exceptionally ferocious. Her mere roars of rage caused the entire underworld to tremble!

"This is never going to end... Ereshkigal, you can take care of these two. I'll be right back..."

Upon seeing this change, Gilgamesh looked at Ereshkigal and murmured something. Then, the king collapsed to the ground. Fujimaru Ritsuka hurriedly helped him up, but saw that the king's eyes were not closed and the flesh he touched was getting cold. This indicated that the king of Uruk was dead, and the cause of death was exhaustion from operating the 360 ​​giant crossbows.

"No...something's not right?!"

However, at this moment, Ai Lei blinked in confusion and whispered:

"I didn't see this guy's soul in the underworld... Ah!!!"

The reason Ereshkigal screamed was not Gilgamesh, but the ominous black mud that surged like a tsunami towards Ereshkigal's location in the underworld, which was amplified by the resurrection of the Mother Goddess. It seemed to be trying to corrupt the spirit of this goddess of the underworld.

However, the moment the chaotic tide surged, two figures rushed towards Ereshkigal's location. In the instant the wave crashed down, there was no one there. At the same time, in the distance, Gensou appeared on the boulder with Ereshkigal and Ishtar in his lap. Ishtar moved less than Gensou, so the boy also grabbed her and carried her away from there.

"What should we do about this?!"

Regardless, Genjiro and Ishtar are both Servants, unlike the living beings like Fujimaru Ritsuka and Mash. Therefore, their presence here did not cause any disturbance in the relevant Netherworld reaction mechanisms. However, compared to the Netherworld, the ridiculously powerful Mother Goddess Tiamat, along with her constantly produced black mud and hordes of magical beasts, undoubtedly gave Ishtar a headache so badly that she almost tore her hair out.

The South American goddess's spirit origin was damaged in the recent outburst. Even though she hasn't returned to the Throne of Heroes, she doesn't possess much combat power. In fact, it's quite remarkable that she could fulfill her duty of protecting Gilgamesh while being sent to the Chaldea Master by Genji. She can't be expected to cause any further harm to the Mother Goddess. As for myself...

Ishtar and Ereshkigal both looked at Gensou. Although they were helpless, it seemed that they could only place their hopes on him for the time being. The boy understood what they meant and nodded silently without saying anything.

but!

Genji knew that relying solely on his Servant form was absolutely insufficient to contend with Tiamat in her current state, so... there was only one method he could try, but he needed some time to prepare.

Seeing Genji take out 'Luna', Ereshkigal and Ishtar, who had been instructed beforehand, exchanged glances and nodded. Although the enemy in front of them was truly terrifying, since it was Genji's request, they had no choice but to comply. Even if it meant risking their lives, they had to buy him enough time!

However, just as Ishtar and Ereshkigal were watching the black mud surge forward again, intending to forcefully evaporate and repel it with magic, a petal suddenly fell from the sky and landed in the black mud. In the blink of an eye, the terrifying and eerie tide of chaos transformed into a blooming sea of ​​flowers. Seeing this, Romani breathed a sigh of relief and whispered:

"coming."

"They've arrived? Could it be?!"

Fujimaru Ritsuka blinked, seemingly guessing something, and exclaimed in surprise. Before she could finish speaking, a familiar voice reached everyone's ears:

"Yay, we made it!"

A court magician in white robes fell into the underworld and reappeared amidst a sea of ​​flowers. The white-haired nightmare, wand in hand, smiled at the mother goddess Tiamat before her and said:

"Since it's black mud meant to nurture life, let it bloom. The operation was a great success. You truly live up to my brother Merlin's reputation."

"Merlin, how...no, where did you come from?!"

Ishtar asked in surprise, while Merlin first glanced at Gensou, which was bathed in moonlight, and then replied with a smile:

"I am the real deal, Merlin, who came all the way from Avalon!"

"You ran here!?"

"Ereshkigal exclaimed in surprise," Merlin said with a smile, raising his finger and shaking it slightly.

"Of course, I hate sad farewells the most..."

"Excuse me for interrupting you, Tiamat, Tiamat has spread her wings!"

Romani stared in astonishment at the wings that had sprouted as his spirit base changed, and cried out:

"Tiamat is flying away from the underworld!"

334 Nega Genesis (Anti-Genesis)

"Are we going to fly again?!"

Upon hearing this, Ishtar nervously looked towards the mother goddess Tiamat, and sure enough, she saw the unfolded horned wings. Meanwhile, Romani continued speaking:

"If she were to return to Uruk, the Underworld's defenses would be rendered ineffective, and most importantly, she would revert to her immortal and invincible state!"

"There's no other way, Ereshkigal, get ready, it's our turn to attack!"

"Don't be nervous, goddess from heaven."

Just as Ishtar was pulling her sister along, preparing to try and stop the Mother Goddess Tiamat, Merlin's leisurely voice came from the side. The court magician looked at the Mother Goddess Tiamat with considerable emotion and said softly:

"The hatred and sorrow of being abandoned because it was useless to human history, and the resulting rewriting of the Earth's ecosystem. The joy of returning to the Mother of All Things, in its essence, her role is revealed in all its clarity at this moment. The Mother of Creation is not her true name, but the great calamity abandoned by humanity and completely rejected by human history, one of the seven evils of humanity, the beast with the principle of return, is Beast II. Therefore, the conditions for 'him' to appear here have been met, the 'world' weapon to fight against the beast of suppression!"

At this point, Merlin raised his wand high, looked at Tiamat, and shouted:

"Look up at the sky, O primordial sea, your Grim Reaper stands there!"

"what?!"

Ishtar and Ereshkigal looked up and saw the figure standing above the Mother Goddess. It was the old man who had met Genji twice before. Genji had asked about his existence in the temple before. Gilgamesh said that the man's class was 'assassin'. In this dangerous singularity, it was best to mention his affairs as little as possible. By reducing the appearance of information about his 'existence', the guy could operate more secretly and provide a sure-kill opportunity for the final battle.

And now!

It was at this moment that the assassin appeared. Even though he had already appeared beside the Mother Goddess once, thanks to the previous secrecy, all the creatures that fell into the black mud knew nothing about him. The Mother Goddess's spiritual foundation and powers failed to detect his presence in that brief appearance. This beast probably never imagined that the weapon the 'world' used to kill her had passed by her.

"Without death there is no life; only with death can there be life..."

As the old man whispered, a ghostly blue flame emerged from beneath his cloak, turning his disguise to ashes, and the cane in his hand transformed into a chilling greatsword.

"What you call eternity is not progress, but slumber. The beast of calamity, the evil born of humanity, and the compassion that hopes to return—that is the very foundation that rejects you!"

Flames licked at the tattered clothing, revealing heavy, imposing armor on the old man's body. Fully armed, he resembled a Rider or Saber-class Servant more than an Assassin. At that moment, the Servant raised his greatsword, and amidst the pervasive aura of death, looked at the狰狞 (zhengning - ferocious/hideous) Mother Goddess beneath him and whispered:

"Though I am a god who has fallen into beasthood, since I am the primordial mother, I must repay you with my life. I came from the depths of the abyss to let you taste the death of darkness. I am Hassan al-Sabah, the Old Man of the Mountain!"

The Old Man of the Mountain, also known as the Mountain Elder, was the original Hassan al-Sabah. However, the other eighteen Hassans, as well as the followers of the order, did not know the true identity of this figure, nor did they have any evidence of his actual existence.

However, he is the legendary assassin who appeared when the contemporary Hassan al-Sabah went astray and beheaded him. Even the Hassan who killed Hassan is called 'King Hassan' by some!

At this moment, the Assassin, shrouded in ghostly flames and bestowed the name 'Grand' by the 'World', delivers a declaration of judgment upon even the creator god, and the primordial mother of the returning beast:

"By the will of Heaven, your wings are stripped away; your immortality ends here. Listen, the evening bell tolls your name!"

The Grand Servant leaped from the boulder, the death knell echoing through the underworld. Beneath the skull mask, flames of death flickered in his eyes, reflecting the image of the Mother Goddess Tiamat. The greatsword in his hand was also shrouded in a terrifying phantom.

But at that moment, Merlin suddenly sensed something, his brow furrowed, and his wand emitted a hazy yet intense light. Cherry blossom petals instantly outlined a mesmerizing magic spell, unfolding around the Old Man of the Mountain. Almost simultaneously, several dark lights flashed beside this Grand Servant—the 'Eleven Demonic Beasts'! They were 'new humans' reborn from within the mother goddess Tiamat!

And compared to the previous ones, these new ones are much stronger; their bodies, except for the spider legs and wings on their backs, are practically identical to human bodies, and...

Seeing the 'Eleven Demonic Beasts' transform their arms into giant pincers, Merlin's expression immediately turned serious. He looked at Ishtar and Ereshkigal and said in a low voice:

“These guys are the real ‘Sons of Tiamat’ now. Each of them is probably no less powerful than the Demon God Leader. You need to be careful and stall for time!”

Before he finished speaking, Merlin drew a sword from his wand and charged toward the nearest eleven monsters. Although this guy was a candidate for the Grandcaster, King Arthur Artoria was taught swordsmanship by him, so he was quite capable in close combat.

On the other side, Ishtar and Ereshkigal also joined forces to attack. Merlin's words were not wrong at all. These new 'Eleven Beasts' were incredibly strong. Ishtar, who was best at aerial combat, was completely suppressed in just a few rounds. The mistress of the heavens was suppressed without any room for counterattack. She could only scream and protect her head with her arms, indiscriminately attacking in all directions with her divine aura and magic power. But even so, the wounds on her body were increasing rapidly.

Fortunately, Ereshkigal temporarily repelled the monsters attacking her. With a swift movement of her hands towards Ishtar, crimson magic instantly transformed into shackles, binding the enemies who were attacking her sister. Ishtar seized this opportunity, piloting her celestial vessel to annihilate all of them.

However, the power of the 'Eleven Beasts' exceeded the expectations of the two goddesses. Ereshkigal's restraints were indeed successful, but the 'Eleven Beasts' twisted their bodies like eels and escaped from the restraints. At the same time, terrible stray bullets were shot out from the wings on their backs, making Ereshkigal dare not easily defend against them.

On the other side, Merlin, holding a staff in one hand and a sword in the other, struggled against the combined attack of two 'eleven magical beasts'. Fortunately, the advantage of being proficient in both magic and martial arts was that he had a wide variety of tricks up his sleeve. Although it was strenuous, he was not about to be defeated. He spared some attention to Fujimaru Ritsuka's side. She was doing well. The South American god was doing a good job of protecting her. If she had more time to rest, she might be able to be used as a fighting force.

"I'm telling you, this is absolutely not going to work!"

Covered in blood, Ishtar teleported to Merlin's side and said weakly:

"Look at that assassin, he's trapped by a large number of monsters too. What's the point of stalling for time like this!"

"You seem to have misunderstood something."

Merlin wiped the sweat from his brow, smiled at Ishtar, and said:

“I’ve always said that we’re stalling for time so that King Hassan can get closer to the beast. Have you forgotten that we still have a powerful fighter who hasn’t shown up yet?”

"Wait, you mean...?"

"Silly little sister, you've really gotten carried away..."

Ereshkigal couldn't help but complain, but in fact, this mistress of the underworld knew the truth. The moment the 'Eleven Demonic Beasts' appeared, she used the power of the underworld to conceal the location of the Origin Land. It was a method that concealed even the existence and concept of the Origin Land. This power, even though it had been reduced by the mother goddess Tiamat, was only for that creator god who had fallen into beast form. For someone like Ishtar, forgetting was a normal occurrence.

Of course, Ereshkigal wouldn't say this out loud. Since he had a rare opportunity, he had to find a way to talk to his sister about it.

At this moment, as Ereshkigal's power dissipated, the hazy moonlight reappeared, and the figures within were clearly visible. The 'Eleven Demonic Beasts' roared and charged towards the direction of Gengoku. However, before they could attack, a dark figure rushed out from within, easily annihilating the monsters that had been giving everyone a headache. Kamen Rider quickly surveyed the surrounding situation, and the 'Skull' Memory appeared out of thin air on the Lost Driver. After activating its power, the Skull Magnum wielded its power, eliminating the enemies surrounding King Hassan one by one. Then, he nodded to the Grand Assassin, signaling him to act quickly.

"Hey, I said, wasn't that a bit too much for you...?"

Ishtar took the opportunity to come to Genji's side, looking him over and asking him with concern in her voice. Ereshkigal had the same thought. As the goddess of the underworld, she could clearly sense that Genji was not a servant at this moment, but a true living being.

However... the underworld's defense mechanisms seem to have no effect on him. No, that's not quite right. The underworld's powers are perfect and flawless; they are indeed activated. It's just that... there seems to be some powerful force within Gensou, protecting him and preventing him from being drawn into the underworld's powers.