"...Still, this is an incredible castle."

After handing over the children to someone else in the Demon King's Castle, I was guided to a certain room. It seems that because I saved the demon children, there wasn't too much suspicion towards me.

Inside the castle, there were various types of demons. Every time I passed by someone, they stared at me intently. Is there something strange about this armor?

Knock, knock.

"Demon Lord, excuse me."

"Enter."

After the knock, the door opened, and Libera entered with a skeletal figure.

"Demon Lord, I deeply apologize for my previous disrespect. I am known as Debra."

The skeleton introduced himself as Debra. He was one of the Four Heavenly Kings who were present when I was summoned as the Demon Lord. According to Libera, he possesses the knowledge I seek, so I allowed him to join.

That said, he’s the one who tried to experiment on me, so I’m still wary.

"...It seems you haven’t informed the other two, have you?"

"Yes, just as you commanded, Demon Lord!"

As I heard from Libera earlier, after I left the Demon King's Castle, the summoning of the Demon Lord was kept secret among the Four Heavenly Kings and other executives. Well, summoning a human instead of a demon would surely cause a scandal.

And apparently, the other two of the Four Heavenly Kings whom I defeated are furious and searching for me to exact revenge. As expected, they underestimated me and were angry about losing without taking the fight seriously.

If word got out that I had come back to the castle, they’d definitely attack me.

"So, Debra, tell me about the current state of the war between humans and demons."

"Understood!"

It seems that like Libera, this Debra acknowledges me as the Demon Lord. After I left, the two of them discussed how to somehow win me back to the demon side by any means necessary.

It seems they were trying to gather the magical ore crystals I need to return to my world. I’m not sure how reliable they are, but for now, he seems to have the most knowledge in the Demon King’s Army, so I'll at least hear him out.

"First of all, the war between demons and humans..."

As Debra explained the war, this was the general outline:

The war between demons and humans began around 300 years ago. Before that, the territories of demons and humans were clearly divided, and though there were small skirmishes, nothing ever escalated into a full-scale conflict.

There were even nations where humans and demons coexisted, and some people intermarried, suggesting they had a rather friendly relationship.

However, 300 years ago, war broke out, and from that point on, the conflict between the two races grew more intense. It became a brutal struggle, where both sides sought to retaliate violently, washing their conflicts in blood. The barrier between the two races became insurmountable.

The war dragged on for centuries, and little by little, the humans began to gain the upper hand. Though most demons could use magic, giving them individually more power, the humans leveraged their numbers and teamwork to gradually wear the demons down.

Then, about 50 years ago, a savior emerged for the demons. This individual, possessing overwhelming strength, united the disjointed demon factions and declared himself the Demon King, establishing the Demon King's Army.

The appearance of a single demon turned the tide of the war in the demons' favor. They reclaimed lands that had been seized by humans and managed to overturn the losing war into a stalemate. With their momentum, it could even be said that they were at an advantage.

However, the humans didn’t stay quiet. Five years ago, they succeeded in summoning a hero from another world through the Hero Summoning Ritual. With the hero’s overwhelming power, the humans once again took control of the battlefield.

One year ago, in a last-ditch effort, the Demon King challenged the hero to a duel, but even the Demon King couldn’t defeat the hero.

With the Demon King lost, the Demon King’s Army collapsed completely, and the demons were pushed back even further by the humans. As a final resort, they performed the Demon Lord Summoning Ritual, which brought me into this world.

"...I see. A lot has happened in this world too."

"Without the Demon Lord, the Demon King’s Army is fragmented, and we’re in a hopeless situation against the humans..."

"Demon Lord, please save us!"

Libera and Debra knelt before me, lowering their heads. I’m just an average guy, so having people bowing to me doesn’t make me happy; it actually makes me uncomfortable.

"I understand the situation. I’m willing to help the demons to some extent."

"R-Really!?"

Seeing the demon children and other demons, I don’t believe they are inherently brutal or evil. Besides, if there was once a time when humans and demons coexisted, I can’t agree with the humans' mindset of completely eradicating the demons.

Of course, I have no intention of fighting humans head-on or killing them, but I think I can offer some support.

"Yes. But there’s one more thing I need to ask."

While Debra’s explanation helped me understand the war, there’s one thing I absolutely need to know.

"What caused this war to start 300 years ago?"