Sebastian noted Grayfia’s cautious posture, taking mental note of her immediate reaction to defend him.
At the very least, her defensive instinct proved he could tentatively trust her loyalty for now.
Sirzechs remained silent for two long seconds before slowly standing up, his expression extremely cold.
Grayfia tensed, expecting the Crimson Satan to make a hostile move, but instead, Sirzechs bowed his head slightly toward Sebastian.
“Thank you for telling me about this,” Sirzechs said earnestly.
“If possible, I would like to learn any other information you have on Rizevim.”
Sebastian smiled slightly.
This reaction fell completely within his expectations.
In his past life, fans often joked that Sirzechs was practically the reincarnation of God due to his overwhelming goodness and calm demeanor.
Still, Sebastian wasn’t unprepared for a betrayal.
Before leaving his room, he had hidden a Summoned Sword in the dark corners of the Lucifer castle.
Thanks to his modified ability, he could instantly teleport back to that sword from anywhere in the Underworld.
Combined with Yamato’s spatial slashing, he could escape back to his base in less than a second.
If things had gone wrong, he would have extracted Rizevim’s restriction curse, contacted the old monster directly, and ignited an all-out war between Rizevim and Sirzechs.
Fortunately, that extreme option remained a last resort.
Since everything was going smoothly, Sebastian decided to play his role as a double agent to perfection.
“Of course, Lord Sirzechs,” Sebastian replied with a respectful smile, laying out his next set of cards.
“I don’t know every detail about Rizevim’s departure from the Underworld.
However, before he left, he mentioned an organization called the ‘Khaos Brigade.’ He intends to gather the remaining Old Satan faction members to build their strength in secret.
Once the right moment comes, he plans to personally lead them to restart the Devil Civil War.”
Sebastian paused slightly before continuing, “I don’t know which specific Devil clans signed contracts with him, but I recall him mentioning the Naberius Clan and something about an artificial Super Devil experiment.”
Sebastian narrowed his eyes, putting on a confused expression.
His acting skills weren’t master-class, so he kept his reaction minimal, conveying that he was completely clueless about those terms.
In truth, Rizevim had never discussed these secrets with him.
Everything Sebastian knew came from his memories of watching the original story.
He wasn’t entirely sure if the Naberius Clan had already established direct contact with Rizevim yet, but he knew one thing for certain: the Naberius Clan was actively conducting illegal artificial Super Devil experiments, and their current test subjects were two young Nekomata sisters—Kuroka and Shirone—whom he planned to recruit as his future Peerage members.
“Is that so?” Sirzechs nodded slowly, giving away nothing in his expression.
“I have noted your words.
We will investigate these leads thoroughly.
The information you provided is very important, but while you are dealing with Rizevim, you must be extremely careful not to show any flaws.
If he discovers your betrayal, your life will be in grave danger.”
“I understand,” Sebastian replied, looking Sirzechs dead in the eye.
“I genuinely intend to act as Rizevim’s planted spy in the Underworld while secretly reporting his movements to you.
After enduring two massive wars, I truly do not want to see the Devil race dragged into another foolish conflict.”
His words were sincere.
Sebastian needed a peaceful, stable Underworld so he could safely use his Check-In System and grow stronger.
Sirzechs, however, misconstrued his true motive, assuming the young Lucifer possessed a noble, peace-loving heart.
His respect for Sebastian increased drastically, feeling as though he had found a like-minded ally among the younger generation.
After a brief discussion, Sebastian used the excuse of needing to keep his visit low-key to have Grayfia teleport them back to the Lucifer estate.
The moment they arrived back in his room, the system notification chimed in his mind:
[Check-in Objective Complete!]
[Reward Obtained: Devil Trigger (Devil Transformation)!]
Chapter 4: The Power of Devil Trigger
Having already received the Yamato and the Summoned Swords, Sebastian wasn’t surprised to obtain Vergil’s signature Devil Trigger form.
It’s the standard Devil Trigger…
Sebastian thought, clenching his fist as he activated the power for the first time.
Dark magic surged around him as a stylish dark blue coat materialized over his clothes.
Unlike Vergil’s full demon transformation, Sebastian’s form remained largely humanoid.
A pair of sharp, black devil horns swept backward from his head, and glowing blue lines traced their way from his neck up to his chin.
His hands and feet transformed into sharp, demonic talons, while his eyes burned with brilliant blue light.
“All my physical and magical stats have increased dramatically…” Sebastian murmured, examining his glowing hands.
“It feels similar to activating a Sacred Gear’s Balance Breaker.”
In the past, Sebastian was considered a failure within the Lucifer Clan.
While his magic power was weak by royal standards, it wasn’t completely nonexistent.
Now, the moment he entered his Devil Trigger form, his magic power exploded outward.
He estimated that his current power was at least equal to a High-Class Devil, bordering on the threshold of an Ultimate-Class Devil.
More importantly, this was only his first time using the form.
With proper training and mastery, his combat power would skyrocket even further.
Once I fully master this form, I might be able to reach Satan-class combat power directly!
Sebastian thought excitedly, holding back a gasp.
He hadn’t expected a single check-in reward from Sirzechs to yield such a massive boost.
He had assumed the base Devil Trigger would only raise his strength to High-Class Devil level, requiring him to unlock the Sin Devil Trigger later to reach Satan-class power.
This form is far stronger than I imagined, Sebastian thought, casually swinging Yamato through the air as his blue eyes glowed in the dark room.
“Lord Sebastian, are you preparing to go out?” Grayfia asked, walking around the corner of the hallway just as he stepped out of his room carrying his sword.
“Yes,” Sebastian replied smoothly.
“Though I’m not going alone.
If it’s convenient, I would like you to accompany me to the Naberius Clan’s territory.”
Grayfia’s calm face remained stoic, but her eyes flickered with surprise.
“Are you referring to the artificial Super Devil experiment you mentioned to Lord Sirzechs?”
“Exactly.” Sebastian walked toward the main entrance, with Grayfia falling into step right behind him.
“I roughly understand Sirzechs’s situation,” Sebastian explained as they pushed open the heavy wooden doors.
“It isn’t that he disbelieves me, but this matter involves high-ranking Devil nobility.
Once he returns, he has to consult the other Satans before taking official action.
To avoid alerting the enemy, he is forced to move cautiously.”
A cool breeze swept through the courtyard as Grayfia looked at him attentively.
“Lord Sebastian , if the government moves too slowly…”
“Don’t worry, I understand,” Sebastian interrupted, turning to look directly at her.
“Whether it’s the Anti-Satan Faction or the Old Satan Faction, they are both political organizations.
No political faction is ruled by a single voice.
Now that the Old Satan Faction has collapsed, the internal politics of the Anti-Satan Faction are becoming chaotic as well.”
He continued calmly, “Sirzechs might believe me, and he certainly knows this corruption needs to be cleaned up, but he cannot act recklessly—simply because he holds the title of Crimson Satan.”
“Then you…” Grayfia began, stopping mid-sentence as she realized his intention.
Sebastian chuckled softly.
“Me?
I carry the surname Lucifer, but I am not the current Crimson Satan.
Officially, I am a member of the Old Satan Faction.
Whatever action I take today, the political backlash will fall entirely on the Old Satan Faction, not Sirzechs.”
Grayfia closed her eyes, remaining silent as she accepted his logic.
“At the very least, no official noble will dare publicly oppose your actions.”
“As long as it works on the surface, I don’t care,” Sebastian said, turning toward the Naberius territory.
“How they curse my name behind my back is none of my concern.
I live my life doing what I must.
Let’s go, Grayfia.”
“Yes, Lord Sebastian.”
Chapter 5: The Secret Laboratory
Deep beneath the main castle of the Naberius Clan lay a massive, hidden laboratory.
While the estate above ground appeared noble and grand, the underground facility was a nightmare of dark science.
The Naberius researchers were not working on ordinary magic—they were obsessed with creating an artificial Super Devil.
In the entire Underworld, only Sirzechs Lucifer and Ajuka Beelzebub were recognized as true Super Devils, beings whose power far transcended normal Devil limits.
Most Devil families had accepted this reality, but the Naberius Clan refused to yield.
Driven by arrogance, they sought to forcibly manufacture Super Devils through cruel genetic experiments.
They believed that if they could create three artificial Super Devils, they would command the ultimate military force in the Underworld.
With that power, they could overthrow both the Anti-Satan Faction and the remaining Old Satan Faction, claiming the seats of the Satans for themselves.
This grand ambition had driven the Naberius researchers completely insane.
What had started as theoretical magic research had devolved into horrific live-subject experimentation.
The scientists were consumed by a single desire: success at any cost.
At the lowest level of the underground dungeon, a young cat-girl named Kuroka sat on the cold stone floor, holding her younger sister, Shirone, tightly in her arms.
Shirone was sound asleep, her tiny hands gripping Kuroka’s clothes even in her dreams.
Despite her dirty face and exhausted body, Kuroka forced a soft, gentle smile as she looked down at her sister.
Devils are all completely crazy, Kuroka thought bitterly.
She had watched the Naberius researchers transform from respected noble scholars into unhinged monsters.
In her eyes, all Devils shared this cruel, selfish nature.
Gently stroking Shirone’s hair and cat ears, Kuroka’s expression hardened with resolve.
If this dark fire burns me away, I won’t regret dying, she thought, her voice dropping to a faint whisper.
But you’re different, Shirone…
You are the one person I cannot afford to lose.
She had already decided to kill their handlers and break out of the facility, even if it cost her life.
Before she could move, a bright blue light flared in the dark hallway outside their cell.
Massive magical energy condensed rapidly in the air.
Instinctively, Kuroka pushed Shirone behind her.
Sharp claws extended from her fingertips as her cat tail puffed up, her entire body entering a battle-ready stance.
As the blue light reached its peak, two figures stepped out of the portal.
Shirone rubbed her sleepy eyes, looking around in confusion.
“…Sister?”
“Stay behind me!
When I tell you to run, run!” Kuroka hissed.
Using her Senjutsu, she felt a powerful presence instantly appear right beside her.
“Die!” Kuroka screamed.
Combining her raw magic with Senjutsu energy, black flames ignited on her claws as she slashed downward toward Sebastian’s face.
However, compared to her future self, the young Kuroka was far too inexperienced.
Having already activated his Devil Trigger form, Sebastian easily caught her wrist in mid-air, pulling her forward until their eyes met.
“Don’t be so aggressive,” Sebastian said calmly.
Before Kuroka could strike with her other hand, Sebastian spoke a single sentence that froze her in place:
“Don’t be afraid.
It’s over now.
Your terrible days are finished—leave the rest to me.”
At that moment, two vibrant notifications flashed in Sebastian’s vision:
[Check-in Target: Kuroka] Requirement: Subdue Kuroka.
[Check-in Target: Shirone] Requirement: Pat her head.