"The final step... is to add the demon's blood."
As the words fell, a single drop of deep red blood slipped into the test tube, merging seamlessly with the bluish liquid inside. The once clear reagent transformed before their eyes, turning a vivid sky blue—the color of a clear summer sky.
"We did it!"
Tamayo and Shinobu stared intently at the mixture, joy flashing in their eyes as they exclaimed in unison.
"Now comes the true trial," Shinobu said solemnly.
"Yes... the final test," Tamayo agreed, her voice steady but calm.
They both knew that even though the reagent had merged successfully with demon blood, the real question remained—would it work?
"Tamayo-san... you don't mean—"
"I'll do it, Shinobu," Tamayo said gently, cutting her off.
Shinobu's face tightened with worry. Though both had worked through countless trials to perfect this formula, and theoretically it should work, using it on a demon—especially herself—was another matter entirely.
"It's alright," Tamayo said, sensing Shinobu's concern. "I've already made up my mind."
She smiled faintly, a mix of serenity and resolve in her expression. "And, Shinobu, could I trouble you to cover for me for the next few days? Just tell them I'm busy with research."
Tamayo hadn't shared her decision with anyone else. Only Shinobu knew—and not because Tamayo told her, but because no secret could ever slip past her sharp gaze.
Together, they had spent countless nights adjusting the ratios of the reagent, hoping the Blue Spider Lily serum would blend flawlessly with demon blood. And now, with success within reach, Tamayo was ready to be the first test subject.
Not just because it was her formula—she would be the one to most accurately gauge the effects. But more than that… Tamayo longed for the day she could stand in the sunlight. If this succeeded, she would no longer be a shadow in the dark—she could truly be beside Yohan.
"I haven't forgotten my hatred for Muzan Kibutsuji," Tamayo thought. "But now... I have something else. A new hope, a new reason to live. And I believe... Yohan will help me sever the chains of my past."
That evening, as the Butterfly Mansion settled into quiet, Tamayo lay still on a cot in the lab, while Shinobu sat vigil beside her.
"Then… I'm going to begin," Shinobu said, lifting a syringe.
"Go ahead," Tamayo nodded.
"I'll see you soon, Tamayo-san."
"Yes... see you soon, Shinobu."
With that, Shinobu gently injected the serum. Tamayo tensed slightly, brows knitting together—then slipped into a deep sleep. Her body remained still, but a rising warmth beneath her pale skin and subtle changes in her expression hinted that the serum was taking effect.
"Come on, Tamayo-san. Everyone's waiting for you."
Shinobu sat beside her, eyes never leaving Tamayo's form. Her heart swelled with admiration.
From fear to partnership to profound respect, her view of Tamayo had completely changed.
"The old me would've struck down any demon I saw. But now… I'm guarding one."
"No... not a demon—a person."
To Shinobu, Tamayo was now fully human.
Thanks to her cover, the rest of the mansion believed Tamayo was buried in her final phase of research. No one suspected anything was amiss during the days she stayed hidden away.
But by the fifth day, Shinobu began to worry.
"She should've woken up by now…"
Had something gone wrong?
She checked Tamayo's vitals—heart steady, breathing calm, all signs normal. Still, the wait gnawed at her. Shinobu began examining the leftover serum, hoping to find a clue.
Then, she heard a sound.
She rushed to Tamayo's side.
"Wha—!?"
"You're awake, aren't you!?"
Tamayo's eyes fluttered open, her pupils now completely black. "Hello, Shinobu."
She slowly sat up, her body still sluggish from days of rest. But there was no mistaking it—she was awake, alert… and different.
"How do you feel?" Shinobu asked, eyes wide with cautious hope.
Tamayo smiled brightly. "I feel wonderful, Shinobu. Our research… may have truly succeeded."
Her body pulsed with strength. For the first time in centuries, she felt warm. It wasn't just the fading chill of a demon's cold blood—it was life surging through her veins.
"I want to go outside," Tamayo said suddenly, determination in her voice. "I want to feel the sun."
"So soon? Shouldn't you rest a little longer?"
Shinobu hesitated. If the serum hadn't worked, direct sunlight would mean instant death. The risk wasn't small.
"I'm ready. I can feel it—I'm different."
Tamayo stood slowly. Shinobu followed at her side, bracing herself for the worst.
"It's daytime out there now. Tamayo... are you sure?"
Tamayo nodded firmly. "Open it."
Shinobu gritted her teeth, took a deep breath—and pulled the door open.
Golden sunlight flooded the room.
Tamayo stepped forward—and the light bathed her.
Shinobu squeezed her eyes shut, terrified she might hear a scream, see her friend vanish into dust.
But instead—
"Shinobu! Look!"
Tamayo's voice rang out, clear and elated.
Shinobu opened her eyes.
Tamayo stood in the full light of day, wearing her deep purple kimono, radiant as the morning sky. Her black hair shimmered like silk, her figure calm and strong. She spun in place, like a butterfly dancing beneath the sun.
"We did it! We really did it!!"
"Ahhh—!"
Shinobu couldn't help herself—she ran forward and tackled Tamayo in a hug.
Despite their age difference, in that moment, Shinobu felt like a child hugging her older sister.
"Haha, Shinobu... let's go! Let's tell Yohan and the others right away!"
Tamayo's heart was soaring. For the first time in her long life, Muzan Kibutsuji faded from her thoughts. All she wanted was to share this joy with him.
"Yeah! Let that bastard see what we've accomplished!"
Shinobu nodded eagerly, sharing Tamayo's triumph.
Moments later, in the garden—
"You… what… is this?!"
Yohan sat reclined on a lounge chair, blinking as two familiar figures approached him.
Tamayo. Shinobu.
Standing together under the sun.
"Tamayo?! How… how are you standing in sunlight?!"
"Because the serum worked, you dummy!"
"She's right, Yohan. Your plan—it's working!"
Yohan stared in disbelief.
Of course—Tamayo must have taken the serum in secret. He now realized the odd silences, Shinobu's strange behavior—it all made sense.
"You… you really went and did it without telling me…"
He sighed, more exasperated than angry. "Don't do that again. If something went wrong—what then?"
He glared at them, but beneath it all was concern.
"There were safer ways, Tamayo. You should've waited."
Tamayo smiled sweetly, stepping closer.
"You understand why I had to do it… right?"
Her voice was soft, almost a whisper. Sunlight danced across her features, and Yohan thought she had never looked more beautiful.
"…Sigh."
"Welcome back to the light, my Tamayo."