Long ago, when the Earth was very young and fragile, there existed a peaceful realm where Guai, humans, and gods lived together in harmony. This place was full of lush lands, sacred temples, and divine presence, and it was considered a paradise.
But one day, a human trespassed into the Realm of Hell, unknowingly offending the powerful entities that guarded it. The gods of the four hells — guardians of punishment and balance — saw this as an affront.
炎獄 (En-goku) – Hell of Flames: Lava rivers, volcanoes, and fire demons. Punishment through fire and trial by burning.
氷獄 (Hyō-goku) – Hell of Ice: Frozen wastelands, glaciers, and frost beasts. Punishment through isolation and slow despair.
暗獄 (An-goku) – Hell of Shadows: Endless darkness, phantom assassins. Punishment through fear, illusions, and regret.
腐獄 (Fu-goku) – Hell of Decay: Swamps of rot, plagues, and undead horrors. Punishment through corruption and destruction.
In retaliation, the hell gods unleashed their wrath on the human realm, bringing destruction with a terrifying yet controlled precision. The chaos was immense, and only the most powerful god of death, Yanruo Wang, intervened.
Yanruo Wang defeated the hell gods and sealed them in different regions of the Earth:
South, East, West, and North, each containing the remnants of their hellish power.
The human who caused the offense was returned to Earth, but the Guai had already infiltrated the mortal world, living among humans in secret. Over time, humans learned to coexist with these beings, who carried the energy of Shijoku — the underworld power, Meiryoku.
The realm of Shijoku is no ordinary place. Those who are born within it, or carry its essence, are immortal by birth, for it is the destiny of Shijoku to grant life beyond the limits of time.
Shijoku exists between the human world and the world of the Guai, acting as a bridge of energy, life, and spiritual power. From this realm flows Meiryoku, the source of all power, connecting humans, monsters, and gods alike.
It is in Shijoku that the fate of all beings is intertwined — humans who trespass, Guai who wander, and overlords who rise — for whoever holds the essence of Shijoku holds the key to immortality, power, and the balance of world
Diazo Dori slowly opened his eyes, blinking against the morning light. His heart raced, still caught in the remnants of what he had seen.
"What… was that?" he whispered to himself. "A dream? Or… something else?"
He shook his head, trying to make sense of the fleeting images. Faces, places, powers — and then, unexpectedly, he saw his old friend again. The vision vanished, leaving only the faint echo of Shijoku in his mind.
"Maybe… it was just a dream," Diazo muttered, taking a deep breath. But deep down, he knew it was more.
"I… am Diazo Dori," he said, his voice firm. "A Kaijin. That is who I am… and who I have always been."
He stood tall, eyes blazing with resolve. "And now… I will be the teacher of the next generation of Kaijins. They will learn, they will fight, and they will protect the balance between humans and Guai… as I once swore to do."
Diazo Dori yawned as he walked down the sunlit footpath. "Another day… and another dream," he muttered. "Could the world really be like that? Is it possible?"
Birds chirped in the trees. Cars passed by. People hustled through the streets. "Maybe today I should do something… after all, it's my first day as the teacher of the Kaijins. I need to be polite with them," he thought. "Last year, things didn't go smoothly… but now? I can do it right."
As he walked, a commotion caught his attention: a thief was holding up an old woman's bag.
"Hey! Give me your money!" the thief demanded.
"Help!" the woman cried.
Diazo sighed, adjusting his posture. "Really, people. You shouldn't abuse your power like this," he said calmly.
The thief sneered. "Who are you?"
Diazo smiled faintly. "You may have heard of me. People call me Diazo Dori, but you… you can call me Mr. Polite. Doesn't it suit me?" He stepped closer, positioning himself between the thief and the woman.
"You think you can fool me?" the thief growled.
"I'm not here to fool anyone," Diazo replied evenly. "Now… put the gun down. Help is better than violence. Or… I will call the police."
The thief's eyes narrowed. "I'll shoot!"
Diazo raised a single hand. The bullet froze in midair, hovering inches from him.
"What… what is this?" the thief stammered, eyes wide.
"You really tried to shoot us?" Diazo said, unimpressed. "Disappointing. I don't like showing my power to ordinary people — rules are strict — but when someone needs help… I step in."
The thief panicked and tried again. The bullet froze again, this time sinking harmlessly into the ground. "No… it can't be! You're a monster!"
Diazo tilted his head. "Monster? Perhaps. But I'm polite too." He raised his hand again, and the gun gently flew from the thief's grip into his own palm. "You should never threaten my friends, or the innocent. Now…"
The thief trembled. "Please… don't hurt me!"
Diazo smirked. "Run if you like. But it won't be easy." With a calm flick of his wrist, the thief collapsed into a sleep-like state.
Diazo picked up the woman's bag and handed it back. "Here you go, Granny."
He turned, only to find… she had vanished.
Diazo blinked, scratching his head. "Wait… what? She ran? I wanted to help…"
He made a funny face, shrugging at the empty street. "Well… at least the Kaijins will learn from this. Politeness… and power."
Diazo Dori shrugged, his expression calm. "Guess… if I show my power, it might cause a scene," he muttered, placing the bag carefully on the police station counter.
After all his training as a Kaijin, he had grown incredibly strong. It showed in everything he did — careful, precise, and powerful. "We are Kaijins after all," he thought.
As he walked down the street, he muttered quietly, "I've lost so many things in life… a friend I wanted to see again. But… I guess I can't have them back."
A ball rolled across his path. A young girl picked it up and looked up at him.
"Is something wrong, mister?" she asked softly.
Diazo shook his head with a faint smile. "Nothing at all." He showed his face, and the girl immediately blushed.
"Wait… what? Why is he so… handsome?" she whispered.
Diazo tilted his head, his calm voice echoing gently. "Is something wrong?"
Another girl appeared, holding her notebook. "Hey Yori, everything fine?" she asked. Her eyes widened as she caught sight of Diazo.
"Wow… he's really handsome," she whispered.
Diazo smiled politely. "Wow… hey, girls."
The girls giggled, some leaning closer. "Can you… be with me?" one asked.
"It's okay to have feelings," Diazo said lightly, giving them a gentle smile.
"Hey, can we take a picture?" another asked.
Diazo chuckled softly. "We can talk later. I have somewhere to go now."
And with that, he started running down the street. "Run, run… bye!"
The girls called after him, hearts fluttering. "Wow… he's so handsome!"
Diazo smirked, a hand on his head as he ran. "Phew… that was close," he muttered.
Diazo Dori sighed, looking at the path ahead. "My life… I guess I can finally say it's taken a turn. I was feeling bad when I thought about my past… but now? I'm the teacher of the Kaijin Academy. Finally… we're here."
He approached the academy door and reached for the handle. Just as he was about to open it, a strange feeling prickled his senses.
"Something feels… fishy," Diazo muttered, eyes narrowing.
He paused, taking a cautious step back. Suddenly, a girl's voice came from behind:
"Gotcha!"
Diazo spun around in surprise. "What—?"
Before he could react further, a familiar face appeared. He caught her hand gently, recognition dawning.
"It's me… Sera. Your love," she said with a teasing smile.
Diazo blinked. "Oh… it's you? My bad, I didn't see you there."
Sera stepped closer, playful and confident. "My love, where have you been? Don't you want to cuddle?"
Diazo's eyes widened, and he made a funny face. "No thanks… why should I?"
Sera pouted, tilting her head. "We're couples, aren't we?"
"Wait… when did that happen?" Diazo asked, genuinely confused.
Sera giggled, nudging him gently. "Aww… don't you want to cuddle me, naughty man?"
Diazo crossed his arms, suspiciously. "Hmm… something's fishy here."
Sera's eyes sparkled, teasing. "Fishy? What's so fishy?"
Diazo tilted his head, a faint smirk forming. "You… suddenly calling me your love and wanting to cuddle? That's fishy."
Sera laughed, leaning closer. "So… you do care!"
Diazo just sighed, shaking his head with a funny face. "This is going to be a long day…"
Diazo Dori shook his head, brushing off the lingering thoughts from earlier. "Anyway… where are the new students? I want to meet them."
Sera smiled mischievously. "They're already in the room," she said, watching him with amusement.
Diazo strode confidently to the classroom door and swung it open with a flourish.
"Well helloooooo, students! It's me, your teacher… Diazo Dori!" he called.
Silence.
Diazo blinked, looking around. The classroom was… empty. No students. No chairs moved. Even the desks seemed untouched.
"Wait… what?" he muttered, his face frozen in a mix of confusion and frustration. His usual calm demeanor slipped into a comically blank stare.
Suddenly, a duster swung out of nowhere and hit him squarely on the head, leaving white dust in his blond hair.
"What?! Was that a trick?!" Diazo exclaimed.
Before he could react, a rope was thrown over him, tangling around his arms. "Hey! Who did that?!"
From the back of the room, a group of students giggled. "So… this clown is going to be our teacher? What a drag," one whispered.
Diazo narrowed his eyes, tugging at the rope. "Hey! I am not a clown, you three idiots!"
Another student, smirking, added, "Uh… I think you kind of are…"
Diazo sighed, pinching the bridge of his nose. "This is going to be a long day…"
One of the students leaned back, smirking. "So… you're done? What's your name again?"
"Daizo," he replied firmly.
The students exchanged glances, then one said with a grin, "We're going to knock you out!"
Diazo raised an eyebrow, calmly tugging at the rope still tangled around him. "You three are messy," he said, a small smirk forming. "And… you're in trouble."
The students paused, impressed but not intimidated.
"That's a very good trick," Diazo added, chuckling.
Just then, another student appeared from behind, voice teasing: "But won't that be enough? You know…"
Diazo, suddenly seated on the sofa with a calm, almost smug smile, looked down at them.
The students froze, shocked. "What… how?"
Diazo's smile widened. "It's Genso, you know…"
The rope around him vanished, and the Diazo who had been tangled disappeared, replaced by a fully free and relaxed version.
"But…" he continued, eyes narrowing slightly, "I still have to say… you three are troublemakers."
The students gulped, realizing that Diazo Dori was far more than he appeared — polite, funny… and extremely powerful.
Diazo crossed his arms, a calm smile on his face. "So… tell me. Are you ready?"
One of the students blinked, still wide-eyed from the earlier chaos. "Wait… how did he… do that?"
Another student whispered to the group, eyes shining with excitement. "That's Genso! It's his illusion skill… he can trick other Kaijins with it!"
The first student's jaw dropped. "No way… our teacher can do illusions?!"
Diazo, noticing their awe, chuckled softly. "Yes… Genso. But don't get used to it. I only use it when necessary. Now, focus — it's time to train."
The students gulped, realizing their polite, funny, but insanely powerful teacher was far more than they imagined.
Diazo Dori adjusted his posture, a calm smile on his face. "So… tell me. What are your names?"
The boy with striking blue hair spoke first, voice confident but respectful. "I'm Kaito Nakamura."
The boy with black hair followed, nodding. "I'm Hamura Yamato."
Finally, a quiet, serious-looking boy spoke. "And I'm Sei Sakurai."
Diazo's eyes sparkled with a friendly warmth. "Well, well… it's very nice to meet all three of you. I'm your teacher, Diazo Dori. Let's make sure your time here at the Kaijin Academy is… unforgettable."
The three students exchanged glances, a mix of excitement and nervousness bubbling up.