When Leo and his group boarded the train to the Underworld, the sky was only just beginning to brighten.
So even after arriving at their destination and taking some time to rest and reorganize, there was still plenty of time left in the day.
Under Leo's instructions, the members of the Eligos servants began their morning foundational training.
Only—right from the start, the intensity was cranked all the way up.
"Boom!"
With a thunderous roar, a massive blast of demonic power came crashing down from the sky, slamming into the ground and triggering a huge explosion.
"Ahhhhhhh!"
Yukino, Asuna, Utaha, and Mahiru screamed as they scrambled to escape, barely avoiding a direct hit.
"Run! Run faster! Don't slow down!"
Leo, his eight devil wings spread wide, hovered in the air as he chased after the four girls. At the same time, he kept forming enormous demonic power blasts in his hands and hurling them in their direction.
"Boom!" "Boom!" "Boom!" "Boom!" "Boom!"
Explosions erupted one after another behind them, forcing the girls to flee in panic, their screams filled with fear.
"What are you doing?!"
"Is this really necessary?!"
"This is way too dangerous!"
"Stop it already, senpai!"
Yukino, Utaha, Asuna, and Mahiru shouted their protests, but all they got in return was Leo's merciless response.
"Wasn't it written clearly in the plan? The purpose of basic training is to force out your daily limits—and then surpass them, reaching a higher level."
"If I just had you run laps, sure, it would improve your stamina. But devils have far stronger bodies than humans. How long would you have to run to actually hit your limit?"
"That would be a waste of time, and the efficiency would be terrible."
So Leo chose to use danger to stimulate their bodies, to force out their latent potential—pushing them to their limits faster, then breaking past those limits under the surge of adrenaline.
"This doesn't just improve stamina, it boosts demonic power too. When you're pushed to the brink, a devil's demonic power becomes extremely active—much easier to train, and much easier to strengthen."
Leo flapped his devil wings as he pursued them, massive demonic power blasts forming around him.
"If you want to get strong fast, stop complaining! Run! Faster! As fast as you can!"
"And don't forget to circulate your demonic power—use it to protect your bodies and activate it as quickly as possible!"
"Otherwise, you're going to suffer."
As he spoke, Leo showed absolutely no mercy, continuing to bombard them with demonic power blasts, sending the girls into even louder screams.
"This is insane!"
"This is way too much!"
Their complaints only made Leo's assault even fiercer.
This deadly game of chase continued for a full two hours.
Only when all four girls were gasping for breath, collapsing onto the ground with no strength left, did Leo finally stop and land in front of them.
"Don't relax yet. Physical training is done, but demonic power training is still going."
Like a true Spartan drill instructor, Leo pushed them without mercy.
"Now, keep squeezing out your demonic power. Release it outside your bodies and manifest it in the form you're best at. Move!"
Under his urging, the girls forced themselves back to their feet despite barely being able to breathe, gritting their teeth as they released their demonic power.
Yukino manifested hers as ice.
Asuna shaped hers into blades.
Mahiru manifested flames.
Utaha simply released her demonic power directly, condensing it into a dense mass.
But the moment they succeeded, Leo suddenly released his own demonic power. The overwhelming surge formed a chaotic force field that instantly disrupted their control, causing all of their manifested demonic power to explode.
Short, sharp screams rang out as the backlash sent all four girls tumbling to the ground.
"Again," Leo said coldly. "You must be able to maintain long-term demonic power manifestation and release even under my interference. That's how you increase both your total demonic power and your level of control."
"Especially after intense consumption, when your demonic power is already active—progress will be even faster."
"Hurry up. Don't waste time. Every second you waste is a second of growth you lose. Are you really okay with that?"
Grinding their teeth in frustration, the girls still forced themselves up again and continued releasing demonic power.
Explosions echoed again and again, mixed with the girls' pained cries—it sounded pitiful.
"I'm already starting to regret joining this servant team!" Utaha even shouted, making just how brutal the training was painfully clear.
But there was no such thing as regret in this world.
None of them were mentally fragile, so they all endured, pushing on until noon finally arrived and Leo called a halt.
"Rest for an hour. After lunch, you'll begin your individual targeted training."
The moment those words left his mouth, the girls all collapsed flat onto the ground, completely spent and unable to stand.
Their stamina and demonic power were utterly drained. Body and mind exhausted, they didn't even have the strength to sit up and eat.
"Looks like going this hard on the first day might've been a bit too much," Leo muttered, scratching his head—though he had already expected this outcome.
He summoned several familiars and had them bring over the prepared lunch, feeding the girls directly.
As they swallowed the food with difficulty, they quickly noticed something surprising—their bodies were rapidly recovering.
"What is this?" Asuna asked curiously. "Why does it feel so warm going down? Even the fatigue is disappearing really fast."
"Did you add something special?" Mahiru asked in surprise, sipping her bowl of miso soup. "It tastes like medicinal herbs."
The two girls most interested in cooking immediately pressed him for answers, prompting a small smile from Leo.
"This was inspired by something Asuna gave me before."
Previously, Asuna had obtained tea leaves from Miyamoto Musashi—tea that could eliminate fatigue and restore energy. Musashi had used it frequently during her own training to improve efficiency.
Remembering this before they set out, Leo discussed it with Miyamoto Musashi to see if it could be used for this special training.
Musashi didn't give a direct answer, but she did report the matter to the Underworld.
The next day, Musashi informed Leo that the Four Great Maou were already aware of his plan to bring his servants back to the Underworld for special training, and had decided to provide them with some special resources to assist.
The ingredients used in today's lunch were part of those resources.
"Food that quickly restores physical vitality has been added," Leo explained. "You'll be back to full strength in five minutes. From now on, breakfast, lunch, and dinner will all include this, so you won't be immobilized for days after intense training."
"Eat up. You'll need the energy for the rest of the training."
Leo turned and left, while the girls stared at each other for a moment before hurriedly taking their lunches from the familiars and eating.
"Do we really have to live like this for a whole month…?" Yukino muttered without thinking.
The others froze.
Even so, they quietly finished their meals, let their bodies fully recover, and rested where they were.
An hour passed quickly.
Right on time, Leo appeared in front of them again, making all four girls shudder.
"Don't look at me like that. Next is your individual targeted training. Even if I wanted to interfere, I couldn't," Leo said, rolling his eyes. "But I've prepared suitable training grounds for each of you. Follow me."
Under Leo's lead, the girls spread their wings and took to the air, flying off in different directions around the camp.
Before long, each of them arrived at their assigned training area.
Yukino's was an ice cavern, filled with extreme cold and dense ice-attribute demonic power, perfect for training with Absolute Demise.
Mahiru's training ground was an area saturated with intense light power. Simply being there caused the purple flames within her to surge out uncontrollably, forcing her to calm her mind and maintain control.
Asuna's training field was a land littered with broken ancient swords. Each blade carried the lingering demonic power of its former wielder—something any swordsman could draw insight from.
As for Utaha, her training area was just an empty field. Leo required her to fill it entirely with barriers she created herself, and every setup had to be different, honing her sensitivity to barriers.
With that done, Leo truly had no way to interfere further. These trainings could only be completed by the girls themselves.
Only then could Leo finally begin his own training.
"I'm not wasting this month," he said quietly.
And with that, Leo charged into the Ancient Battlefield.
Before long, thunder and lightning began to roar in the distance.
=-=-=-=-=-=-=
You can read up to chapter 175 on patreon.com/NiaXD.