Gurgle.
Ryūhei Ubuyashiki's charred head fell to the ground, rolling a few times before gradually shriveling and turning to ash.
Shinji's expression was cold and resolute.
His strike was clean and decisive, without a trace of hesitation.
Knowing his death was imminent, Ryūhei had been subtly laying traps for Shinji—either luring him to attempt soul extraction or tempting him to follow Ryūhei's path of invading other worlds to delay the destruction of his own.
Thus, Shinji acted swiftly, slaying the scheming wretch who harbored ulterior motives even in his final moments.
"He wasn't afraid of my soul extraction, likely because his body is now thoroughly permeated with the Hegemon's power. If I tried to extract his soul, I might have been tainted by the Hegemon's influence."
Shinji thought to himself.
Ryūhei was far too cunning. Faced with such a scoundrel, Shinji had no choice but to abandon his plan to extract more information from him.
Boom!
At that moment, a bolt of thunder roared across the sky.
Shinji looked up and saw that the lightning hidden in the clouds was a chilling scarlet!
"What a pity. This world is beyond saving…"
Shinji let out a faint sigh.
The Hegemon's power had fully infiltrated the Demon Slayer world, making its destruction only a matter of time.
With a flicker of thought, Shinji vanished from the spot with a whoosh.
Some time later, he arrived at a concealed underground palace.
Undoubtedly, this palace was the most critical of Ryūhei Ubuyashiki's many bases. It housed not only his laboratory but also his secret vault.
Having read Ryūhei's memories, Shinji easily bypassed the base's defensive traps and entered its interior.
After exploring the laboratory, Shinji took out a sealing scroll and packed away all of Ryūhei's century-long experimental records and materials. Among them, he even found the legendary Blue Spider Lily.
Clearly, as the "Lampbearer" of the Demon Slayer world, Ryūhei had collected every treasure this world had to offer.
Having nearly packed up the entire laboratory, Shinji moved on to Ryūhei's personal study.
There, he discovered that Ryūhei, the Demon King, had also been researching "Blood Demon Arts," with research notes filling over a dozen bound volumes.
"Excellent!"
Flipping through the materials, Shinji's spirits lifted.
At its core, Blood Demon Arts could be seen as an advanced application of blood and flesh power. In the Demon Slayer world, they represented the pinnacle of power.
Some Blood Demon Arts involving spatial manipulation elevated the technical application of the Demon Slayer world's power to a whole new level.
Even in the shinobi world, capable of moving mountains and seas, "Space-Time Ninjutsu" was an exceedingly rare and advanced art!
Beyond the Blood Demon Arts materials, Ryūhei had also amassed a vast collection of data on Breathing Techniques.
He had gathered dozens of Breathing Techniques, from lesser-known ones like "Beast Breathing" and "Flower Breathing" to the origin of all Breathing Techniques, "Sun Breathing."
Shinji suspected that Ryūhei had collected every Breathing Technique from every school in the Demon Slayer world.
Moreover, it wasn't just Breathing Techniques. Ryūhei had also researched related secrets like the "Mark" and "Fighting Spirit."
He had even conducted detailed studies and written extensive commentaries on the swordsman's highest state, the "Selfless State."
In his notes, Ryūhei described the Selfless State as the process of a swordsman elevating their "technique" to the level of "the Way."
This wasn't a state achievable through mere training or slaughter. It required a swordsman to reflect and comprehend day after day, integrating their insights into their swordsmanship and grasping a fleeting spark of enlightenment to unlock this ultimate state.
Once achieved, a swordsman in the Selfless State could sense an enemy's killing intent, conceal their own, and perceive their opponent's weaknesses, gaining the ability known as the "Transparent World"!
However, Ryūhei noted with regret that even swordsmen who reached this state remained mere mortals, forever bound by the constraints of aging, illness, and death.
Even someone as great as Yorichi Tsugikuni couldn't escape the fate of dying of old age!
"Not bad, not bad!"
Reading through the materials, Shinji's eyes gleamed.
For someone like him, who wielded chakra, what he needed were higher-level techniques and states of being. The Selfless State, for instance, could greatly enhance his strength if he mastered it.
Unlike Blood Demon Arts, which required becoming a demon to use, this martial arts state wouldn't interfere with Shinji's chakra cultivation.
Regaining his focus, Shinji followed the information gleaned from Ryūhei's memories and searched a corner of the study, locating the mechanism to open a secret chamber.
Click.
With a mechanical sound, the chamber's door slowly opened.
Shinji was about to step inside but paused, suddenly thinking of something. He formed hand seals and performed the "Shadow Clone Jutsu," keeping his real body outside while sending a shadow clone into the chamber.
This wasn't an unnecessary precaution.
As a former "Lampbearer," all of Ryūhei's information related to the role was influenced by his "Lamp," existing in an "encrypted" state. Even Shinji's Rinnegan-powered soul extraction couldn't easily decipher those memories.
This secret chamber was likely tied to the "Lampbearer" role. While Shinji had found the method to open it in Ryūhei's memories, the contents of the chamber remained encrypted in Ryūhei's soul.
The unknown represented risk, so Shinji sent his shadow clone in first to investigate.
Inside the chamber, the shadow clone quickly noticed a large display rack.
On it were countless items, many of which Shinji couldn't name or guess the purpose of.
Some of these items clearly didn't belong to the Demon Slayer world, their bizarre designs exuding an eerie aura.
Approaching the rack, the shadow clone saw labels and thought, "Just as I suspected!"
Undoubtedly, the items on the display rack were all plundered by Ryūhei from the worlds he had traversed.
However, these items weren't extraordinary artifacts or imbued with magical powers.
They were merely remnants—traces of broken worlds, of civilizations conquered and slaughtered, proof of their past existence.