In one of the many rooms of Suria Castle, a certain prince slowly opened his eyes after a long slumber. As he gradually regained his consciousness, his vision was met with the blank white ceiling of the room and noticed the weak rays of light coming from the window beside his bed. He slowly lifted his head and upper body before a slight headache bugged him, forcing him to massage his head to remedy the pain. The memory of what happened before he ended up in this room was a blurry.

"Helios! You're awake." the voice of a young boy said, accompanied with the sound of a door opening.

Helios turned towards the door to see a blue-haired boy, who he knew as his master, Hikaru Asahi. But he saw another figure he recognised standing beside the boy, a green-haired maid carrying a tray containing a teacup and a few tea cakes. Both of them went to Helios' side, with the maid setting down the tray on a small table beside the bed.

"Hikaru..." Helios uttered before turning to the maid. "Oh, and you."

"How are you feeling?" the maid asked.

"A bit dizzy...I don't seem to remember what happened before this."

"You don't remember? You and His Majesty defeated an army of devils that were trying to invade The Heart last night."

At this, those blurry memories started to become clearer bit by bit. It was a headache to remember at first, but the more he thought, the better he could recall that event. The image of him and his father resonating with their respective bladers to defeat the evil army eventually became clear as day.

"Ah, I remember now," Helios said. "I must've passed out after using a lot of my energy in the fight."

The prince then wanted to get out of bed with the intention to meet Hyperion, but the maid stopped him.

"Where do you think you're going?!" the maid yelled at the prince.

"To see my father." Helios simply replied.

"But you're still recovering!"

"I can stand up!"

"What happened last night took a great toll on you! You're not leaving this room until you've fully regained your energy!"

He groaned frustratedly. "Can you at least tell me what my father is up to today?"

"His Majesty is preparing to go to the Underworld to interrogate the devil that attacked the city last night."

Hearing this, Helios immediately became silent. If there was one place in Aether he wouldn't want to go to at the moment, it would be the Underworld. Not that he was afraid of the constant darkness that shrouded that region, but he just didn't want to cross paths with a...certain spirit who held a high position there.

"Am I required to go there?"

"Yes."

This made him more irritated. He really did not want to go there. But, given that those devils were after the bladers, he figured that he would make this one trip just for Hikaru's sake.

Helios sighed. "When will my father depart for the Underworld?"

"His Majesty said that he will wait for your recovery before he leaves."

"Father must really want me to come along if he's waiting for me. How...considerate." Helios thought.

"I understand. You may leave." he said to the maid.

The maid simply bowed before turning to exit the room. As she was going through the door...

"Wait." she heard the prince, causing her to turn around to see him giving a soft smile to her.

"Thank you for bringing the food to me, Rhodus."

The maid smiled back before exiting the room and closing the door behind her.

The prince sunk back into his bed, finally able to enjoy some calming silence. That was until...

"So, her names Rhodus, huh?"

The voice startled Helios, causing him to yelp a bit. He turned to his side to see his blader standing beside him.

"Hikaru, you're still here?!" Helios almost yelled.

"I was here the entire time, but you completely ignored my existence when you started talking to that maid." the boy answered back with a poker face.

"S-Sorry..." Helios covered his face with his hand, trying to hide the fact that he was blushing.

Hikaru chuckled. "It's okay, I won't question it. Besides, it's not nice delving into other people's personal lives."

Helios sighed in relief. He was lucky that Hikaru's parents taught him well.

"Thank you."

🔸🔸🔸

Hours passed and the crown prince of Aether was now set for the mission to the Underworld. Accompanied by Hikaru, Helios made it to the main hall of the castle where the other bey spirits and bladers were gathered. Hyperion was the first to notice his arrival and promptly greeted him.

"Ah, you're here," Hyperion said. "Have you rested well, Helios?"

"I have, father," the prince replied. He then noticed the other bladers standing among them. "Are they following us?"

"I did tell them to stay here, but they insisted on coming with us."

"Of course!" Aiga said boldly. "Those devils had business with us!"

"Yeah! It's only fair if we know what they're up to too!" Drum added.

To the spirits, there partners did have a point. All of them were mixed up into this mess. If anything, leaving the children in the dark would only put them in more danger.

"Your argument is logical. However, given that all that has transpired recently have been centred around you five, your safety should be of more concern." Helios said.

Hyperion came forward. "Which is why I am giving you these." The king summoned a decorated box out of thin air. The box opened, revealing five silver rings, each adorned with a red sun emblem.

"Wow! These rings look so cool!" Valt said with sparkles in his eyes.

"So, we need to wear these in the Underworld?" Aiga curiously asked as he picked up one of the rings.

"Not just in the Underworld, but at all times. These will protect you if you are threatened." Hyperion explained.

"Oh, so these can ward off bad guys?" Hyuga questioned.

"Something along those lines."

Understanding how the rings work, the bladers slid the small jewellery onto their fingers. They are all now set to go to the Underworld.

🔸🔸🔸

It only took a short while for the group to reach the entrance of the Underworld. It was located west of The Heart, not far from the hill where the bladers started their journey in Aether. It was a large opening with sharp stalagmites and stalactites that made the mouth of the cave resemble the jaws of a monster. The sight of this gargantuan cave made the boys conscious of their size.

"So, this is the entrance to the Underworld?" Valt asked in awe, with a bit of nervousness in his heart.

"That's right," Valkyrie replied. "I know it may look scary, but trust me, the Underworld is a safe place. I've been here many times before."

The group proceeded to descend into the dark cave, following a winding path that traveled deep down into the abyss. The boys were a bit wary at first, but when they caught the sight of clusters of glowing crystals and mushrooms hanging on the walls of the cave, they couldn't help but be amazed by their radiance and iridescence. It helped to distract them from the worries of walking down into the darkness.

After an hour of walking, they reached a large black stone gate. As if sensing that there were visitors, the gate opened by itself. Suddenly, a giant creature emerged from the gate. It resembled a dog with rough dark green fur, its eyes glowing red. It had three heads, all with chains on their necks. The middle head had a metal eye covering on its right eye. Upon exiting the gate, the hound let a loud howl that echoed throughout the cave.

"WAAAH!!!" the boys screamed, startled by the beast's appearance.

While the boys were panicking, their partners didn't share their reaction. In fact, this beast that was in front of them was someone they recognised all too well.

"Hi, Kerbeus!" Valkyrie greeted.

"Kerbeus?" Valt and Aiga said in sync, as both of them were familiar with the name.

"That is correct," the three-headed dog, Kerbeus, spoke through his middle head. "I am Kerbeus, Guardian Hound of the Underworld! All that wishes to enter this realm must pass through me first."

Kerbeus leaned forward towards the two older bladers and began to sniff them. He backed away once he was done.

"This scent. Why is it so familiar?" the hound questioned before he heard Valkyrie chuckled.

"You've forgotten already? The blue one's Valt and the red one's Aiga. One of your bladers is an old friend of Valt's and the other one is Aiga's...uh..." she leaned over to the brunette. "What's your relation with that masked guy?"

"Oh, you mean Kyle? He's kind of a weird guy." he answered back.

"I'll take that as a rivalry."

Suddenly, they heard a booming laughter coming from the triple headed beast.

"I remember now," he said. "Oh, now I feel so ashamed to have forgotten about you while Ken has not. My deepest apology. As for Kyle...I'd rather not talk about that sly fox."

"It's alright. I'm just glad to hear that Ken still remembers me." Valt responded with chuckle.

"Wait, you have two bladers? Is that even possible?" Hikaru asked.

"It is indeed possible," Kerbeus answered. "Bey spirits can have more than one master. Those who choose to do so have the advantage of not immediately dying after one of their beyblades are broken, though it does greatly reduce their power."

"Wait, if that's the case, then what if all your beys are battling against each other. Do you like, fight yourself or something?" Hyuga questioned. Such a concept was slowly but surely frying his brain.

The hound groaned. All of these questions were starting to irritate him. "Look, I don't have time to explain the whole concept of The Oath to a bunch of children whose brains melt faster that ice! Especially since the king is here." Kerbeus then turned to look at Hyperion. "I reckon that you have very important matters to attend to here, Your Majesty?"

"Correct," Hyperion replied. "We are here to interrogate a recent prisoner of Tartarus."

"I see. Then I shall not waste your time. Though I believe these humans probably will."

Hyperion laughed at this retort. "Oh, I don't mind, as long as the job gets done."

After that exchange, the group were given entry to the Underworld. What was behind the gate was not what the bladers expected. Through the gate was an entire city! It was similar to The Heart, but it was underground instead. The boys scanned their surroundings with amazement.

"Wow! There's an entire city down here!?" Drum exclaimed with sparkling eyes.

"Indeed. This is Elysium, the hub of the Underworld. The majority of spirits here are miners, resource gatherers and Tartarus prison guards. This city was built to smoothen all the work and business that happens here." Hyperion explained.

The group followed Hyperion down a specific path through the subterranean city. On that path, they encountered a man, one that was once again familiar to the spirits but not to the bladers. His outfit appeared to be very regal, with a black dress coat adorned with purple and magenta buttons and pendants, signifying that he must have a sort of high status. He had black and magenta hair that was tied into a long loose ponytail, coupled with emerald green eyes. He also had a pale complexion.

"Your Majesty," the man spoke as he slightly bowed before the king. "I have received the news of your arrival in advance."

"Oh, come on, Lucifer. This is between family. No need for formalities." Hyperion casually said to the man. He then turned to the others. "Boys, let me introduce you to Lucifer. You may know him as the beyblade of Lane Valhalla. He is the current Lord of the Moon and oversees all that happens in the Underworld."

At this, the man, Lucifer, stared at the bladers with a neutral expression, recognising them as the boys he and Lane once faced off against in the Ultimate Tag Series.

"It is an honour to meet you, legendary bladers." he greeted, his face remaining the same.

The boys didn't know what to say to the spirit. They initially felt a bit afraid of Lucifer as he and Lane caused quite the uproar in the blading world, coupled with the fact that he was once the royal family's arch nemesis. But since Lane had changed his ways following his and Shu's battle against the Asahi brothers, perhaps it was safe to assume that Lucifer also changed.

Valt, being the most mature out of the five, was the first to greet Lucifer properly.

"It's an honour to meet you too!" he said as he came forward and extended his hand to the spirit with a smile.

Lucifer definitely did not expect to get a hand shake from The Legend of Legends himself, someone who his blader once greatly despised and sought to overthrow. Regardless, that was all in the past. He accepted the gesture and shook hands with him.

However, someone didn't really seem to like their exchange.

"Ahem," a cough resounded. Lucifer and Valt turned to the source of the sound, only to learn that it was Helios, who had a sour expression on his face. "Are you done yet?" he bluntly said. "We are here to interrogate a devil who almost killed hundreds of innocent lives, not forge friendships."

The prince's passive aggressive remark was met with an audible sigh from his father, a disapproving glance from the other spirits and a stare from the bladers that was a combination of shock and concern, especially from Hikaru. It was clear that Helios did not want to be involved in ANY situation that has Lucifer mixed up in it. It was no wonder that he didn't want to go to the Underworld at first.

Lucifer, however, understood the prince's hatred towards him. After all, it was he who attempted to steal the throne from Hyperion and broke the hearts of the Asahi brothers by breaking the father and son. He had done many atrocious acts even before he became a bey spirit. It was only through witnessing the bond that the two royals shared with their partners as well as the success of Shu Kurenai in saving his student did he realise that all of his actions were worth nothing in the end. Now, he strived to make amends for his past atrocities, knowing that not everyone was going to accept the new him, that included Helios.

He maintained a straight face despite Helios's retort. "Ah, right. Please, come with me." he said.

Lucifer led the group down a path which led them deeper into the Underworld. Eventually, they reached a large imposing gate guarded by two gargoyles. Above the gate was some text, written in a script unknown to the boys.

"Uh, what does it say up there?" Drum whispered to the spirit that was nearest to him, which was Dragon.

"Abandon all hope, ye who enter here. That's what it says." Dragon answered.

Just that translation sent chills down not only Drum's spine, but the other boys' spines as well. That line alone gave them a good idea of what was behind the gothic gate.

By Lucifer's orders, the gargoyles opened the gates of Tartarus. The group followed the spirit into the dark prison. The path seemed to curve downwards in a spiral pattern. When the bladers looked below, they saw hundreds and hundreds of prison cells, spiralling down into a deep dark abyss. Some of the cells were empty, while others had devils imprisoned within them.

As they were walking down the spiral path, devils who were within the cells along that path began snarling at the sight of the boys, angry and frustrated at the fact that they couldn't reach them and hurt them. Some were even clawing at the metal bars. This obviously made the boys afraid and uneasy.

"Worry not," Lucifer reassured, his tone directed to the bladers. "I swear upon The Divine that not a single one of them will touch you."

They eventually reached a hallway that branched off from the main spiral path. It led them to a single cell, lit by a single glowing crystal chunk. In the cell was none other than the raven devil who was responsible for last night's attack.

"I'm guessing this is the one you're looking for?" Lucifer asked the group.

"That is the one alright." Hyperion confirmed.

"Then I will leave you with the interrogation. If you need anything, please inform me." With that, Lucifer left the area.

The group turned their attention back to the feathered monster, who was undoubtedly dismayed by their presence. When they came up to him, he simply glared intensely at them.

Hyperion was the first to speak to the devil.

"So, I am confident that you know exactly what we are here for."

The devil did not respond, so the king continued.

"First of all, tell us your name."

However, the devil only scoffed. "You're delusional to think that I will tell you anything!"

"Either that or we will have to resort to this." Hyperion revealed a small sachet.

At this, the raven laughed. "Oh, are you going to bribe me with gold? And here I thought you were a righteous one, Hyperion."

Hyperion chuckled at the notion. "Oh, no no. This is not gold, but it will get you to talk wether you like it or not."

"Wh-Wha-"

Before he had the chance to question further, the raven devil found himself dowsed in a cloud of a powdery substance. He tried to swipe the dust away from his nostrils but it was already too late. He went into a coughing fit as he struggled to keep the dust out of his lungs but to no avail. The feathered fiend eventually succumbed to the dust, his expression appearing dazed.

"H-Hyperion, what did you do to him?" Hyuga asked nervously. He never expected his partner to do something like this.

"Oh, it's just some hypnotic dust, made from grounding a special kind of plant. As the name suggests, anyone who inhales it will become entranced for a period of time and will answer to any question or command. I personally don't favour this method. However, these are trying times, so getting answers straight away is crucial." Hyperion explained before turning back to the raven. "Now, tell us your name."

"Malphas." the now hypnotised Malphas answered in a monotone voice.

"Alright, Malphas, care to tell us your reasons for attempting to invade The Heart?"

"To capture the humans that have made themselves known to this realm and to seize the forbidden knowledge."

"Forbidden knowledge? What's that?" Valt asked.

"It is knowledge that mortals cannot comprehend, brought down to Earth thousands of years ago by someone who we call The Fallen One." Valkyrie answered. "It has the ability to make any desire a reality...at the cost of one's sanity. Our ancestors weren't able to destroy it, so they locked it up in the catacombs beneath Suria Castle."

Hyperion continued his questioning. "What do you intend to use them for?"

"To revive our lord."

"Who is your lord?"

"The Serpent King, Typhon."

The mentioning of that name made everyone in the group silent, especially the spirits. It was a name they knew from the scrolls of their history.

"Typhon? He's the evil general who went to war against your ancestors, right? Valkyrie mentioned him before." Hikaru chimed in as he had recalled the story the female spirit had told him and his friends before.

"That's correct," Dragon confirmed. "Typhon was defeated by The Noble Four. But the truth is, he isn't really gone. His soul still remained and caused havoc, so they decided to seal him in the deepest depths of Tartarus."

"Wait, that guy's here?!" Drum exclaimed.

"Yep, at the very bottom of this hell hole." Achilles said, moving his index fingers in a circular motion before pointing downward.

Back to Hyperion, he asked further. "By what means do you wish to revive Typhon?"

"Through the ails of mankind." Malphas answered. "Death, despair, disease, destruction - all of these is what my lord craves for. Through the suffering of humanity, we wish to revitalise him."

The group was understandably disgusted by this revelation. To think that they would go to such lengths to revive an ancient evil. But if they were followers of Typhon, who was the figure they referred to as "mistress"?

"But your lord has been imprisoned here for centuries. With that in mind, who do you and your fellow devils answer to?"

"Mistress Echidna."

"Who is she?"

"The Serpent Queen. The lover of my lord."

Hyperion and the other spirits became silent at this answer. They were not aware that Typhon had a lover. As far as they knew, there were no records of her what so ever.

The king wanted to ask Malphas further, but before he knew it, the hypnotic dust's effects had already worn off and the devil had returned to his normal self.

"So, have you already forced enough words out of my mouth?" Malphas retorted at the king.

"Eh, he's back to normal!" Drum stated.

"Can't you throw that dust at him again?" Hyuga questioned Hyperion.

"No," the king shook his head. "The dust can only be used again after a certain period of time as the one who was effected by it gains a temporary immunity to it."

"Darn it! We can't get anymore information out of him!" Aiga frustratedly said.

The spirit king stood there for a moment as he pondered at the information Malphas had given to them. After awhile, he turned to his companions and said:

"Worry not. Though there are still questions that are unanswered, we can still work with what we have."

Hyperion then called out to Lucifer, who instantly appeared behind the group in a mist of purple.

"Anything you need?" the dark spirit asked, his sudden voice starling the bladers.

"Woah! You can just show up like that?!" Aiga blurted out. His words gained no response.

"I've decided to end the interrogation here. However, if you have time, perhaps you could do me a favour and carry out your own investigation. Please inform me if you find anything of interest." Hyperion said to Lucifer.

"Will do." Lucifer replied back.

Satisfied, Hyperion turned his attention back to the boys and the other bey spirits. "Alright, everyone. That will do for today. Let's had back to the castle."

With the interrogation concluded, the group of ten headed for the prison gates, leaving Lucifer behind with Malphas.

"Naive. So naive." Malphas was heard muttering, which caught Lucifer's attention.

"Seems like you have more to say. Why don't you spit it out?" Lucifer retorted.

"Heh, you know that I'm still immune to that dust. There is no way you can get anything out of me-"

Before Malphas knew it, a large black claw was already covering half of his face, threatening to tear his head off. Through his spared eye, he learned that this claw belonged to Lucifer.

"That is only because you were lucky enough to have His Majesty's mercy. I, on the other hand, cannot guarantee that you will receive the substantial amount of mercy as you have received from him." Lucifer said darkly, his eyes glaring deeply into Malphas' soul. "What I can guarantee is a slow, painful beheading should you choose to remain silent. So do choose wisely."

Malphas eye widened in fear and his feathery body was shaking. Either face a painful execution or betray his mistress by telling them everything. He decided to...

🔸🔸🔸

"Hey, Hyperion."

"What is it, Hyuga?"

"I heard you said to Lucifer that you two were family. What's that about?"

"Oh, uh...truth is...he is my uncle."

"WHAT?!"

"Well, not biologically. My father was adopted by Lucifer's mother, which in turn made him his brother."

"Oh...but he looks younger than you."

"Uh...spirits tend to start aging when they have children or when they are nearing the end of their lives."

"So...your saying that Lucifer's single?"

"Yes-Wait, who taught you to say that kind of sentence?"

"Aiga!"

The Scarlet Supernova felt a sudden tremor.