Akira's eyes narrowed, "What did they do, seriously?" He asked, but he had a feeling the answer was going to be ominous.
Selena tilted her head playfully, her smile never fading. "To explain that, first I have to explain about the castle we're in. Brother, what do you think of it?"
Akira glanced around, scanning the dark crystalline walls that were glowing faintly under the light of the stars, the sheer atmosphere of the castle. He muttered after a moment of thought, "The outer walls are made with Nocturnite, the interiors with Lunite, and the throne itself… Asterite. It's almost like this entire place is an artifact."
Selena's grin widened. "Knew you'd notice. You're right. This entire castle is an ancient artifact created by our ancestors. Its name is Axis Mundi Nexus. You can just call it Castle Nexus for short. It's a powerful artifact that connects to the Imaginary Tree and allows us to travel to any world. During the war, this place wasn't just a castle; it was the main operating base. When the war was over, it became the capital city."
Akira's eyes lit up with excitement. "So they made something like this… what else can it do? Is there anything else they made? Can you show me?"
Selena smirked knowingly. "Sorry, brother, but this castle won't suddenly turn into a giant robot. It can do many things, but not that."
"Ah, I see..", Akira looked a little disappointed at that for a moment, then blinked in confusion. "…Wait. I never said anything about a giant robot, did you read my mind again?"
Selena winked. "I know you, brother, I don't really need to read your mind to figure out what you were thinking." She pointed at Erika. "Look, even Erika-chan agrees."
Akira turned to Erika, who gave a small, guilty nod. "Yeah… I was actually waiting for you to say that."
Akira slumped. "Wow. Am I really that easy to read?"
Selena patted his shoulder teasingly. "You are. But let's not get sidetracked again. Let me finish."
Her playful tone softened. "This castle, and this entire dimension, were created by our ancestors. Not just this one, they made many others too. But remember what I told you before? Our powers weakened after marrying into other races. Artifacts like this can only be fully controlled by true Asterians, those with both pure bloodline and pure soul. By the time the second war began, the most they could manage was basic functions. Even the great seal that separated the Tree from the Sea of Nihility could only be repaired by a true Asterian."
Her smile vanished. "And our ancestors knew sealing it wouldn't last forever. If the enemy broke it once, they could do it again. So they needed something more permanent. But to do that, they required a true Asterian… which they no longer had."
Erika raised her hand timidly. "Wait… didn't you say Asterians were born from the Imaginary Tree itself? Couldn't it just make more?"
Selena shook her head. "No. The production stopped after the first war ended, and it didn't restart during the second. The Imaginary Tree isn't as active as you think. It's more passive. Even in the first war, it only created Asterians after countless worlds were destroyed. Think of it this way: the Imaginary Tree is like a person, the Oblivions are viruses, and we Asterians are the white blood cells. Once the attack ended, it stopped making more. Sure, the Tree would eventually create more, but by the time that happened, countless worlds would be gone. Our ancestors couldn't let that happen."
Her expression darkened. "So… they did something drastic. The elder generation, more than half of them, sacrificed their lives. With that sacrifice, they activated all the bubble dimensions under their control and created a massive seal over the cracks in the barrier. They fused worlds together into a final bastion, sealing the breach. But they didn't close it completely. Instead, they created a new world between the Tree and the Sea. A buffer. Before the Oblivions could reach the Tree again, they would have to go through that world. And since they already had an opening, they wouldn't need to make another one. All the Star Chasers were placed there, tasked with fighting endlessly to hold the line."
placed there, tasked with fighting endlessly to hold the line."
Akira's brows furrowed. "Wait. But what if the Oblivions killed all the Star Chasers? Wouldn't they just break through?"
Selena's eyes gleamed. "Brother, do you remember the training ground in our basement?"
Akira blinked. "Yeah… wait. Don't tell me…"
Selena gave a small, bitter smile. "Yes. That world was created with the same mechanism. That's how they managed to hold out for this long."
Erika, who had no idea what they were talking about, frowned. "What mechanism?"
Selena explained gently, "The training ground has a system where if someone dies, they simply… respawn again."
Erika's eyes widened in shock. "Wait, really?"
Selena nodded. "Yes. It's used to train children of our family, so they'll forget their fear of pain and death."
Erika paled, her voice trembling. "…Akira… did you go through that too?"
Selena gave her a soft smile. "Of course. Every child does. My brother, too. Actually, he started the very next day after you two first met. It became his daily routine. In fact…" She then proudly added, "…he even holds the record for the most deaths inside that place."
Akira raised a finger proudly. "No need to praise me. You get used to it after dying a few times."
"Used to it?!" Erika snapped, her voice breaking. "Why are you joking now? Are you an idiot? This isn't a joke! You were only seven back then!"
She couldn't understand how casually they were downplaying something like dying. The thought of Akira dying over and over again, every single day, made her chest ache. And worse… she realized how many times she had selfishly dragged him out to play even when he looked exhausted. He must have been tired because of that… because of this.
Her guilt crushed her, and tears welled up before she could stop them.
"W-Wait…Erika, don't cry!" Akira panicked, waving his hands. "I died too many times, so it's not really that much of a problem!"
Selena glared at him. "Idiot brother! That's not how you comfort someone!" She turned to Erika. "Erika-chan, don't worry, it's something everyone in our family goes through, so…so…" She stumbled over her words, realizing she had never been in this kind of situation before.
Akira puffed out his cheeks. "Excuse me, I'm not an idiot! You're the one who brought it up in the first place; that's what started this." He turned back to Erika, his expression softening. "…Don't cry. I'm saying it's really not that bad."
Selena huffed. "How else was I supposed to explain everything without mentioning that?" She faced Erika again, lowering her head. "…Sorry, Erika-chan, I…"
"Both of you, stop," Erika interrupted, wiping her eyes. "Just… give me a moment. I'm a little emotional. Just let me calm down."
The twins went quiet, exchanging a glance before waiting silently.
After a while, Erika took a deep breath. "Okay. We can talk about that later. For now… please, continue explaining."
Akira and Selena exchanged another look, then Selena nodded and continued.
"That world… It's been using the same system. The people there fight endlessly without ever truly dying. That's how they've been buying time. And while they stalled for as long as possible, the remaining Asterians made plans. A desperate plan… to bring at least one true Asterian back. Someone with both a pure bloodline and a pure soul."
Her eyes hardened, and her next words carried the weight of history.
"They called it… Project Sirius."