Akira was sleeping.
He had a really nice dream, though he couldn't recall what it was, but he knew he had slept well for the first time in a long while.
He felt he was hugging something soft… something warm… something that smelled nice.
And whatever he was hugging… was hugging him back.
Akira's half-asleep brain approved of this immediately.
He didn't know what it was, but it was soft, comforting, and he wanted to stay like this forever. When he pulled it closer, it even let out a soft sound.
"…nn…"
Yes, a soft feminine sound slipped from the thing in his arms.
Akira froze.
Hug pillows do not make sounds.
Hug pillows do not breathe.
Hug pillows definitely do not cling tighter.
Slowly, very slowly, his survival instincts activated.
"…This is wrong. Something is wrong. Something is VERY wrong".
He hugged it a little tighter by reflex.
"…ah…"
And then another soft, feminine, very sensual sound escaped from the thing in his arms.
Sleep evaporated from his brain instantly.
"Oh no." He remembered exactly where he was, and the terrifying possibility of what he might be hugging.
He kept his eyes shut. He was too scared to open them and confirm the truth.
If he saw what he thought he'd see…
He might actually die.
So he did the only thing he could do.
He called for help. There was only one person who could save him now.
"Sister… how should I survive this situation?" he telepathically cried.
Selena's voice came in, sounding a little tired.
"Well, brother… there are two things you could do. One: try your best to move away without her noticing, though I don't think that's possible given your current position. And two: accept reality and prepare to receive your punishment."
"There has to be another way, right?!" Akira begged.
"Sorry, brother", Selena replied, calm and merciless. "Sometimes running away is impossible. You have to face this head-on. I believe in you."
"Believe in what?! Me getting beaten up?!"
He sighed internally. There was no escaping this.
The only chance he had was to separate from whatever he was hugging, quietly without waking it up.
So, gathering every last scrap of courage, Akira slowly opened his eyes.
And there she was.
Exactly as he feared.
A cute sleeping face right next to his own, his childhood friend, Erika, lying so close her face inches from his neck.
Pressed against him. Hugging him like a lifeline. Their legs tangled. Her arms wrapped tightly around his chest.
Akira stared.
Erika also slowly opened her eyes, blinking sleepily…
…until awareness hit her. Her sleepy blue eyes met his.
She froze.
Her face turned bright, burning red.
Akira smiled slightly and nervously, as he gave the weakest, most apologetic smile in existence.
"G..Good morning…" he said trying his best to ease the situation.
"KYAAAAAAAAA!!!"
A high-pitched scream rang out an instant later.
BANG!!
Pain bloomed across his back as Akira found himself somehow upside-down against a nearby rock. "Ouch…" he muttered weakly.
Erika, face bright red down to her neck, pointed at him with a trembling hand. "Y..You…!"
Akira quickly raised both hands defensively, well, as defensively as someone inverted against a rock could. "Wait! I was innocent!"
Erika sputtered, "Are you saying I hugged you in my sleep!?"
Akira said helplessly, "I don't know! Ask my sister, she might know!"
Right on cue, Selena's telepathic voice entered their minds, sounding far too amused for the situation, "Well, technically you're both at fault… but Erika-chan is the one who started. She probably thought you were one of her plushies. Also, she did drink a lot of your blood in her sleep."
Both Akira and Erika blurted out at the same time, but with completely opposite tones,
"Really!?", Akira said, a bit surprised, and Erika's voice was completely mortified,
Akira's hand shot to his neck. Even though his wound healed, he could feel where the bite had been, along with a wave of lingering fatigue rolling through him.
"Erika… couldn't you at least tell me before drinking my blood…?"
Erika's face turned even redder, if that was possible. "I…I don't know! I didn't do it on purpose! It was probably an accident...!"
Then Her eyes widened suddenly as she realised where Akira was.
"W…Wait, Akira…the blue spider lilies!"
Akira said, "Huh?"
Then he looked down and froze.
Beneath him, crushed flat under his own body weight, were the blue spider lily plants.
All of them.
Completely flattened.
Akira's eyes widened in horror as the reality hit him.
"NOOOOOOOOOOOOO!!"
His scream echoed across the quiet mountainside.
They spent the next several minutes desperately trying to salvage what they could.
After a desperate rescue mission, they managed to save only a few intact plants.
Akira gathered the surviving ones carefully, storing them like priceless treasures. He also took samples from the destroyed plants just in case, though it was only a tiny consolation.
And so.
Aside from the few specimens Akira managed to save, the blue spider lily was now basically extinct in this world.
Both of them stared at the ruined patch in heavy silence… silently deciding that neither of them would speak of this incident ever again, at least for the time being.
Because shame, because trauma, because the world was not ready to hear what happened.
Since they couldn't fly during the day, they had to use Akira's bike to get back, so the return trip took far longer than expected. By the time they finally reached the Butterfly Mansion, the sun was already high.
As they walked through the gate, Shinobu appeared, smiling lightly.
"Oh, you two are back. Did you finish whatever you went out to do?"
Akira replied, "Yes… I did. Somehow."
Shinobu nodded, then her expression shifted into something more serious.
"Well, I know you just returned, but I need Akira-san's help with something."
Akira asked, "What is it? Something important?"
"Yes," Shinobu said. "Something related to Tanjiro."
Erika stepped forward. "Was it about Nezuko's immunity to sunlight?"
Shinobu shook her head. "No, it's something else. Come with me, I'll explain on the way."
Erika asked, "Am I needed for this?"
Shinobu answered gently, "No, Erika. I only need Akira-san for this."
Erika let out a tired sigh. "Then, Akira, go with her. I'm too tired. I'm going to rest."
Leaving the two behind, Erika headed toward their room with heavy steps.
Akira almost asked. "Excuse me, who drank whose blood the whole night?"
But he decided against it; he chose life.
Shinobu turned to Akira. "Shall we go?"
Akira sighed. "…Alright."
And so, the two began walking down the mansion corridor, down the hallway.
"So, what's going on?" he asked.
Shinobu explained while walking, "Tanjiro's mark on his head… changed shape during the battle with Upper Rank Four, and his strength increased tremendously," Shinobu said calmly. "This pattern resembles historical accounts of marks that appeared on demon slayers' bodies."
Akira listened silently.
"It was recorded that in the Sengoku period, the swordsman who created the breathing styles had this mark. And not only him, during that era, all of the Hashira also developed similar marks. Those who bore the mark were said to become stronger than ever before."
She continued, fingers folded behind her back.
"Furthermore, the records say that once one marked person appears, it begins to spread to others too. But we still don't know how it appears or why. And in this generation, the first marked person is Tanjiro. But he doesn't know how to activate it on others either."
Akira asked. "So you want me to figure out how it works and how to activate it for others?"
"Exactly," Shinobu said with a small smile. "I was hoping you could figure out how this works, and how to activate it in others. Can you do it, Akira-san?"
Akira replied without hesitation. "Sure. It should be possible… but I'll need to run some tests on Tanjiro first."
Shinobu's expression brightened. "I know. That's where we're heading."
So they walked toward the indoor training room and inside, Tanjiro was already waiting.
He greeted them with a bright smile. "Shinobu-san, Akira-san!"
Akira said, "Oh, Tanjiro, you seem lively."
Tanjiro nodded. "Yes! I wasn't hurt that badly in the fight, so I'm fine."
Then he blinked. "Ah…Akira-san, did you… find that flower?"
Akira said, "Yes. It was exactly where you said it would be. Thank you."
Tanjiro waved his hands. "No, really, don't worry about it!"
Shinobu tilted her head. "Flower? What flower?"
Akira replied, "I'll explain later. Don't worry about that for now, first, we need to run some tests."
He looked at Tanjiro.
"Tanjiro, are you ready?"
Tanjiro stood straight. "Alright! I don't know what this is about, but I'll try!"
He took a deep breath.
The mark on his forehead glowed, expanding, shifting and turning into a flame-like pattern.
WHOOSH.
Tanjiro charged forward and cut down a wooden training target with incredible speed.
Akira's mystical eyes analyzed everything.
Tanjiro's temperature, pulse, muscle output, breathing rhythm, all spiking dramatically.
"Alright," Akira said. "Keep it active for a little longer."
He stepped close, took a few drops of blood, checked Tanjiro's temperature, and made quick notes about his vitals.
"Okay, you can relax now."
Tanjiro exhaled, the mark fading as he dropped onto the floor, sweating.
"Are you alright, Tanjiro?" Akira asked.
Tanjiro managed a tired smile. "I'm fine. Just… a bit tired."
Shinobu asked, "Did you get everything you needed, Akira-san?"
Akira nodded. "Yes. Now we can work on how to activate it."
They bid farewell to the exhausted Tanjiro and headed toward the laboratory to begin analyzing their samples.
The Butterfly Mansion's laboratory was quiet, save for the faint bubbling of glass tubes and the soft scratch of brushes against paper.
Lantern light reflected off neatly arranged jars, medical instruments, and rows of notes pinned across wooden boards.
Shinobu sat at the central table, coat folded, pen poised with her usual calm precision.
Akira stood beside her, tapping the wooden surface thoughtfully. His purple eyes glowed faintly as he stared at a sketch of Tanjiro's forehead mark, alongside the vital stats he had written earlier.
Shinobu asked, "Did you find anything, Akira-san?"
Akira nodded slightly.
"A bit. The first clue is his body temperature."
He leaned over the table, pointing at a diagram he had drawn, heartbeat spikes, breath rhythms, temperature thresholds.
"It wasn't random. It awakened under extreme stress, specifically at a near-lethal body temperature. Around 39 to 40°C."
He tapped different points of the graph.
"Heart rate doubled. Respiration became rhythmic. Neural pathways overloaded.
Basically, the body enters an extreme state."
He leaned back and folded his arms.
"I'm pretty sure that if others reach the same internal conditions, they can awaken the mark too."
Shinobu smiled faintly, resting her chin on one hand.
"You make it sound so simple. But most swordsmen would die before reaching those numbers."
"Exactly," Akira replied. "That's the side effect."
He took a piece of chalk and knelt, sketching a rough human silhouette on the floorboards. He circled each point with clear strokes:
Forehead. Heart. Diaphragm. Spine.
"The mark forces the body to operate beyond human limits," Akira explained.
"More oxygen.
More blood flow.
More neural activity."
He drew several arrows branching outward.
"Everything happens at once. It's like burning a candle from all sides."
He placed the chalk down.
"In simple terms… those who awaken this mark will meet an early death."