「Bonded by blood.」
It was a phrase Tatsuya had heard countless times in his old world, mostly when people spoke of unbreakable family bonds. But to him, it had always felt empty. His mother had died when he was only six, taken by pulmonary disease. It happened fast, leaving a void where "family" was supposed to be.
He still remembered the sterile scent of antiseptic in her hospital room. He had been five years old, sitting on her bed with a board game spread out between them. His mother looked frail, her cheeks sunken, but she smiled at him—warm, even if tinged with sadness.
"Mom... you're not going to get better, are you?" he had asked quietly, the kind of quiet only a child uses when they already know the answer.
Her laugh had been soft, fragile. She had brushed the hair from his forehead, her hand trembling. "Tatsuya, there are some battles even superheroes can't win," she'd said, her voice raspy. "But I'm glad I get to spend this time with my little comic book hero. Let's finish the game, okay?"
That room, filled with the faint smell of plastic tubes and daisies—his mother's favorite flower—had never left him. It stayed with him, like a shadow, always reminding him of a time when he had lost before he even knew what it meant to lose.
"Move now, or die!"
Yuki's sharp voice cut through the haze of the memory, yanking him back to the present. His vision cleared just in time to see one of the King Spider's massive legs swing toward him like a battering ram. Instinctively, he raised his stone gauntlet, the leg colliding with a deafening crash.
The force of the blow sent Tatsuya flying across the room. His back slammed into the stone wall, the crack of ribs splintering echoing through the chamber. Blood sprayed from his mouth as he crumpled to the ground, the entire room shaking from the hit. Dust and debris rained down while he struggled to catch his breath, his chest heaving in painful gasps.
"Late on that call, rat," he muttered, wincing as he spat out more blood.
"Call me Yuki," came her sharp reply. "A feminine name for snow in your world, isn't it?"
"Wait... how do you know I'm from another world?" Tatsuya rasped, pain threading through his voice.
"It won't matter if we're both dead," Yuki shot back, the urgency in her voice unmistakable. "Use half of my brain, my sight, and my senses to enhance your combat. You can focus half of your brain on dodging, half on attacking. We can communicate with the other halves. It's all possible through the blood bond."
Tatsuya managed a strained laugh, wincing. "I wouldn't usually trust a rat's brain for anything... but you seem capable enough. Let's do it."
"I am not a rat, you less-than-human!"
The King Spider took another menacing step forward, its grotesque body filling the space, casting an oppressive shadow over Tatsuya. The creature's chittering echoed off the walls, its many legs tapping against the stone floor like a death knell.
But the King Spider had no idea what Tatsuya and Yuki had been planning in those fleeting moments.
Tatsuya rose to his feet, body trembling but not from fear. The red glow in his eye intensified, pulsing with energy. Perched on his shoulder, Yuki's beady eyes mirrored the glow. The bond was complete.
The stone gauntlet on his arm shifted, the rocks reforming into a sharp blade along his wrist. It hummed with power, feeling more like an extension of his arm than a weapon.
The King Spider screeched in fury and charged, its enormous form barreling toward Tatsuya with terrifying speed, the ground shaking beneath it.
Tatsuya's body reacted instantly, his movements smooth and almost autonomous. He darted between the stone pillars with silent precision, his steps swift and agile. The spider's massive legs smashed into the pillars behind him, cracking the ancient stone, but he was always one step ahead, always just out of reach.
The room was crumbling around them, every strike from the King Spider sending debris tumbling to the floor. Tatsuya's movements were instinctual, his body responding to the rhythm of the fight. He wasn't thinking—he didn't need to. His mind and Yuki's were working together, each guiding him seamlessly through the chaos.
Somewhere deep in his consciousness, Tatsuya found himself floating in a black, endless space. It was as if time had slowed, allowing him to drift away from the fight for just a moment. In this space, he was a glowing white figure, abstract, incomplete, while colors flickered and glitched at the edges of his vision.
Yuki sat before him, still in her small rat form, her red eyes watching him intently.
"How did this blood bond even happen?" Tatsuya asked, his voice echoing in the void.
"I tasted your blood back in the altar room," Yuki explained calmly, her tail flicking with a hint of pride. "Several times over the months. I watched as some of my friends scurried over the bloodline and aged to death in an instant. I stayed behind and slowly licked the blood, building immunity. And when you tasted mine after the King Spider attacked me, it completed the bond. Your mana had grown strong enough, and your undead nature activated the blood bonding."
Tatsuya frowned, taking in her explanation. "Undead... right. I'm a ghoul. But how's this supposed to help me defeat that thing?"
Yuki's whiskers twitched, her voice almost smug. "Patience. The plan is already in motion."
Back in the real world, the King Spider roared, its massive legs pounding the stone floor in rage. It hadn't realized it had been lured into a trap. Tatsuya led the creature toward the last standing pillar in the crumbling room, blood dripping from his wounds, his steps shaky but focused.
With a quick slash of his wrist blade, he severed the final support.
The ceiling groaned, the floor beneath them split wide open, and stones tumbled into the cavern below, revealing jagged spikes jutting up from the darkness.
The King Spider, too massive to react in time, plummeted into the pit. Its grotesque body was impaled on one of the spikes with a sickening crunch. Its legs twitched violently, flailing as it struggled in vain, the life quickly draining from its monstrous form. With one last shudder, it fell still, the once terrifying creature now a broken, lifeless husk.
As Tatsuya fell alongside it, the wind roared in his ears, whipping his hair wildly. Yuki clung tightly to his neck, her claws digging into his skin as they plummeted deeper into the cavern below. The air grew colder, sharper, biting at their skin as the ground rushed up to meet them.
Then, through the darkness, Tatsuya saw it—curled near the cave's exit, massive and still, like a waiting predator—the Iguana Monster. Its forked tongue flicked lazily as it sensed their approach, its eyes slowly opening to reveal a predatory glow.
Panic surged through Tatsuya's chest as the cavern floor came closer. "Another boss fight... right after this?" he thought, his heart racing.