Sebastian looked at his target and casually passed the quiet young cat-girl to the maid beside him.
He then gently patted Shirone’s head and pushed her toward her older sister, whom Shirone was clutching tightly.
Sign-in Reward: Physical Fitness Optimization.
This was the first time he had received a reward like this.
As soon as the power took effect, he felt his muscles tighten, and the strength of his Devil Trigger surged dramatically.
Before this boost, his strength was only around that of an Ultimate-Class Devil.
Now, his power was touching the boundary of a Satan-Class Devil.
“Grayfia, let me handle the fight by myself this time,” Sebastian said.
He stood before the cell door holding Kuroka and Shirone, his fingers resting on the hilt of Yamato.
The heavy door was tightly shut.
“If you are in danger, I will step in immediately,” Grayfia replied firmly, her voice devoid of emotion.
Sebastian smiled faintly.
“Alright, I’ll take that as a yes.”
Slash!
A single flash of blade light cut through the air.
Kuroka tensed instantly.
She sensed Sebastian move in that split second, but by the time she tried to follow his movement with her eyes, he was already standing calmly, returning Yamato to its sheath as he turned to leave.
“It’s…
gone,” Shirone said in a small, childish voice, pointing her finger at the cell door.
More than half of the heavy door had completely vanished.
Hearing her sister’s words, Kuroka’s shock turned into an awkward, nervous laugh.
She quickly gave up any thought of trying to run away.
I didn’t expect him to be this strong…
What kind of monster is this guy?!
Grayfia kept a cold, calm expression on the surface as she led the two Nekomata sisters behind Sebastian.
Inside, however, her mind was racing.
Sebastian Lucifer was known as the useless scion of the Lucifer Clan.
He had weak demonic power and a poor physical body.
Even as a teenager, he could not reach the level of a High-Class Devil.
Lord Sebastian has been hiding his true strength all along, Grayfia thought.
That slash was too fast.
If I am not mistaken, it cut straight through space itself and threw the missing piece of the door out of this dimension!
Combined with his form, his power is almost at the Satan-Class.
She recalled how Sebastian had lived under Rizevim’s shadow, how his younger brother, Vali Lucifer, was forced to flee, and how his father had been killed by Rizevim.
Hiding his strength was a wise choice.
At least he survived and remained in the Underworld.
Sebastian walked down the stairs into the massive underground research facility hidden by the Naberius Clan.
He made no effort to hide his presence.
“Who are you—” a guard shouted.
Before the guard could finish, a blue Summoned Sword pierced straight through his forehead.
He collapsed dead on the spot.
“Are you crazy?!” another guard panicked, backing away.
“If the Four Satans find out about this, you’ll pay for it!
The Underworld won’t forgive you!”
Sebastian grinned.
“I was sent by the Underworld.
Did you really think no one knew about your secret experiments?”
He gripped Yamato with his left hand, placed his right hand on the hilt, and slowly drew the blade.
A bright blue light flared in his eyes.
Realizing a fight was unavoidable, twenty-six Devils unfurled their Devil wings and charged their demonic power.
Yellow magic circles bearing the crest of the Naberius Clan lit up in their hands.
Sebastian focused on his enemies.
Draw.
“My power is absolute.”
Sheathe.
Crisscrossing blade marks tore through the room.
Blood sprayed into the air as all twenty-six Devils fell.
None of them had even seen Sebastian draw his sword before their bodies were sliced apart by Yamato’s slashes.
Parts of their bodies fell through spatial rifts, while the rest collapsed onto the ground.
Having used a large amount of demonic power, Sebastian shifted out of his Devil Trigger and returned to his human form.
With a bright smile, he turned his back on the room full of dead enemies and walked back toward Grayfia.
Kuroka turned pale and quickly covered Shirone’s eyes.
“Sister, what happened?” Shirone asked.
“It’s nothing…
the bad guys are just gone,” Kuroka whispered softly.
Sebastian, Grayfia, and the two Nekomata sisters returned to the Lucifer Clan’s castle through a magic circle.
Sebastian asked Grayfia to arrange rooms for Kuroka and Shirone before heading to his own room to wash up.
As the warm water washed over him, he slicked his hair back.
It was his first time killing humanoid beings, but he felt no guilt or disgust.
Maybe I really am a monster, he thought with a soft laugh.
He snapped his fingers, summoning a magic circle with the crest of the House of Lucifer.
“Sebastian?
Why are you contacting me?” Sirzechs’s voice came from the other side.
“I took care of the Naberius facility,” Sebastian said calmly.
“There are useful materials in their basement.
It was inconvenient for you to act, so I did it instead.
You handle the cleanup.”
After a moment of silence, Sirzechs answered, “You were reckless…
but thank you, Sebastian.”
“No problem.
It’s all for the Underworld,” Sebastian replied with a light smirk.
Later that night, Sebastian walked over and knocked on Kuroka and Shirone’s door.
The door opened slightly, and Kuroka stepped out wearing a loose bathrobe.
“Shirone is asleep.
Let’s talk downstairs.”
Sebastian nodded and followed her.
Kuroka had grown up around the House of Naberius, where Devils were greedy and ruthless.
To her, Devils either wanted to use you or kill you.
Even though Sebastian had saved them, she remained suspicious.
At the landing of the stairs, Kuroka stopped and knelt before Sebastian .
“Lord Sebastian , if you want to use me for experiments or turn me into a weapon, take me alone!
Just please…
spare Shirone!”
She had been subjected to artificial experiments, reaching the level of a High-Class Devil with mastery over Senjutsu and magic.
Yet, after seeing Sebastian ‘s power, she knew she had no chance of fighting or running away.
“Stand up,” Sebastian commanded quietly.
Her body moved on its own, forcing her to stand.
Sebastian sighed.
“I don’t care about experiments, and I don’t treat people like weapons.
I saved you because the Naberius Clan needed to be stopped, and because I will need a Peerage in the future.”
He looked at her directly and held out his hand, summoning a magic circle.
“I am known as a useless member of the Lucifer bloodline, but there is a lot I want to accomplish.
I won’t treat you as a test subject or a weapon.
Kuroka, join me as one of my own.
Will you stand by my side?”
Kuroka looked at the magic circle in his hand.
If she poured her demonic power into it, the contract would become absolute.
Instead of activating the magic circle, she gently brushed it away, causing it to disappear.
Then, before Sebastian could pull his hand back, she took his hand in both of hers and slowly brought it close to her chest.