"While I cannot guarantee success, may I attempt to help her regain her humanity?" Takeru looked at Nezuko, then calmly addressed Tanjiro.
"Huh?! Takeru-san can turn Nezuko back into a human?! Really? Please, I beg you, help her!" Tanjiro was momentarily stunned, then spoke excitedly, even kneeling before Takeru.
"No, I cannot be certain. There is only a possibility." Takeru shook his head.
"I see... Will Nezuko be in danger?" Tanjiro calmed slightly, his worry evident.
"That is uncertain. However, I will stop if any problems arise." Takeru stated honestly, making no promises.
"So there is some risk..." Tanjiro looked at Nezuko, his heart conflicted.
Nezuko was his last remaining sister. He couldn't bear losing another family member.
"Hmm~" Noticing Tanjiro's turmoil, Nezuko looked at him, then at Takeru, and nodded firmly.
"You want to try?" Tanjiro asked worriedly.
"Hmm~" Nezuko simply nodded, her gaze resolute.
"Then... I leave it to you, Takeru-san. What should I do?" Seeing her determination, Tanjiro made his decision.
"Nothing. Just watch." Takeru replied gently.
"Please proceed." Tanjiro sighed in relief. Being able to observe meant he could intervene if necessary.
Rengoku, hearing Takeru's words, watched expectantly. If Takeru possessed such power, perhaps some tragedies could be averted.
"You're Nezuko, right? Come here." Takeru gestured and sat on a seat.
Nodding obediently, Nezuko approached.
Under everyone's gaze, pure light emanated from Takeru's hand. The light gave everyone a sense of cleansing comfort.
Takeru was using his Purification skill. He wasn't certain if Kibutsuji Muzan's demon transformation was a curse or a virus. Purification might neutralize it.
However, if her entire being was composed of such corruption, purification might cause her to dissipate. Hence, Takeru couldn't guarantee success. He started with a very weak version to avoid harming Nezuko.
As the blue-tinged purification energy neared Nezuko, she felt a twinge of fear but closed her eyes, not moving away. She sensed no malice from Takeru.
When Takeru's hand touched her forehead, Nezuko felt a sharp pain… bearable, yet accompanied by a sensation of something dissipating within.
Both Takeru and Tanjiro noticed Nezuko's pained expression. Tanjiro bit his lip but remained still.
Takeru contemplated. Purification had an effect, but fully healing her likely required an advanced, possibly master-level, version.
Without stopping, Takeru intensified the light, using his full purification power.
"Hmm~" As the energy increased, Nezuko's pain worsened, making Tanjiro's heart ache.
Undeterred, Takeru maintained the energy on her forehead.
Considering further, Takeru conjured green healing light in his other hand, also placing it on her head.
As the healing light soothed her, Nezuko's expression relaxed.
Seeing this, Tanjiro also relaxed slightly. While maintaining both Purification and Advanced Healing drained a lot of his MP, Takeru's reserves were ample. The mental focus required for dual casting was also negligible given his high Spirit attribute.
Time passed slowly during the treatment. Inosuke awoke during this period. Seeing the glowing light, he excitedly tried to approach, but a protective Tanjiro swiftly knocked him away...
Ten minutes later, Takeru stopped. Tanjiro immediately rushed over, looking worriedly at the sleeping Nezuko and then at Takeru.
"She is fine. However, my current ability is insufficient to restore her humanity. I could only purify some of the malevolent energy within her." Takeru sighed.
"Malevolent energy?" Tanjiro recalled the dark vapor emanating from Nezuko earlier.
"Yes. That energy drives bloodlust. While she previously controlled it through immense willpower, it was dangerous. If she lost control, she might succumb to bloodlust and destruction. After purification, she should have better control."
"Most importantly, I suspect sunlight's effect on her is diminished, and her regeneration may have improved." Takeru explained.
"You mean... Nezuko can walk in sunlight?!" Tanjiro exclaimed excitedly.
"Not entirely. Prolonged exposure will still be fatal, though the process is slower. The future remains uncertain." Takeru clarified gently.
"Regardless, thank you so much!" Tanjiro knelt again in gratitude.
"You're welcome." Takeru nodded slightly.
Suddenly, Takeru's Observation Haki detected a figure running toward the train. Recognizing it, he smiled.
"We have a guest." Takeru announced lightly.
"What do you mean?" Rengoku, deep in thought, was puzzled. While powerful, detecting a demon from 500 meters was unrealistic.
"Another demon approaches. Its eyes bear the mark [Upper Moon Three]." Takeru stated plainly.
"Upper Moon Three?!" Everyone was stunned.
"Young Takeru, is this true?" Rengoku's breathing grew rapid.
"Indeed. It's now less than 400 meters away." Takeru confirmed.
Seeing Akaza's intent to stop the train forcibly, Takeru used telekinesis to slow it. After all, while he was unharmed, passengers might be injured if the train was stopped forcibly.
"Let's go outside." Takeru suggested calmly.
"Agreed." No one objected, heading to the roof.
Only then did Rengoku notice the missing locomotive. However, his focus was entirely on the approaching Upper Moon Three, not on how the train continued moving.
Despite the white emptiness ahead, Rengoku trusted Takeru's words. If Takeru meant harm, Tanjiro's group would have been dead earlier.