Nezuko intercepted Tanjiro in a secluded corridor as he left the mission planning room. Desperate despite obvious reluctance to voice her concerns.
"Brother, please." She grabbed his sleeve with trembling hands that still bore those strange scratches. "You have to be careful around her."
"Around Akira? Why? What's wrong?"
"She's not what she seems. There's something wrong with her breathing techniques."
"How do you know about her breathing techniques?"
Nezuko's face crumpled with shame and fear. "I can't explain it properly. Not without sounding insane. But she's dangerous, Tanjiro. Promise me you'll be careful."
"Nezuko, you're scaring me. What aren't you telling me?"
"I wish I could explain, but it sounds impossible even to me." Voice broke with desperate pleading. "Just trust your instincts. Don't trust her, no matter how reasonable she sounds."
"You're asking me to doubt a fellow Hashira based on feelings you can't explain."
"I'm asking you to trust your sister." Grip on his sleeve tightened with surprising strength. "Have I ever led you wrong before?"
"Never. But this is serious, Nezuko. If you know something specific about threats to the Corps—"
"I don't have proof. Only dreams. Visions. Things that might not even be real."
"Dreams about what?"
"About her. About demons. About things that shouldn't be possible." Voice dropped to a whisper. "When she breathes that special way... it makes everything feel strange. Like thoughts aren't entirely your own."
"Mental influence?"
"Maybe. Or maybe I'm losing my mind." Bitter, self-deprecating laugh. "Former demon worried about mental stability. How pathetic is that?"
"You're not pathetic. You're the strongest person I know."
"Then why am I so afraid of her?"
"Because your instincts are trying to protect you. Just like mine are trying to protect both of us."
The conviction in his voice seemed to steady her slightly. She released his sleeve but remained close, seeking comfort in his presence.
"I keep having these dreams where she's teaching demons new ways to exist. Ways that don't require killing humans but don't require dying either." Nezuko's voice carried dawning horror. "And the demons in my dreams... they talk about her like she's their salvation."
"Their salvation?"
"Someone showing them alternatives to what they've always been. Evolution beyond their original nature." She shuddered at the memory. "But in my dreams, I can sense what she really wants. What she's really teaching them."
"What does she want?"
"To prove that transformation works in both directions. If demons can become human..." Nezuko's voice trailed off as the implications hit her. "Then maybe humans can become demons. Or maybe both species can become something else entirely."
---
"What will you do?" Nezuko asked, studying his face with desperate hope.
"Whatever it takes to keep you safe. Even if it means questioning people I'm supposed to trust."
"That could be dangerous for you. Going against Corps authority—"
"Not as dangerous as ignoring clear warnings about threats to my family."
"I'm sorry for putting you in this position."
"You're not putting me anywhere. I'm choosing to trust your judgment over protocol." Tanjiro squeezed her hands gently. "Can you tell me what specifically to watch for?"
"When she breathes that hypnotic way... everything feels different. Like she's reaching into your mind and rearranging things." Nezuko shuddered at the memory. "And the demons in my dreams... they talk about her like she's their teacher."
"Their teacher?"
"Someone showing them new ways to exist. Ways that don't require killing humans but don't require dying either."
"That sounds exactly like what she was discussing during our mission briefing."
"You talked about this with her?"
"She brought up theories about demon evolution. Alternative approaches to traditional slaying methods." Tanjiro felt pieces clicking together in his mind. "She seemed very interested in your transformation experience."
"Because I prove her theories are possible." Voice carried dawning horror. "If demons can become human, then maybe humans can become demons. Or maybe both species can become something else entirely."
"What kind of something else?"
"I don't know. But in my dreams, the demons talk about evolution. About becoming more than what they were. About a new teacher showing them possibilities they never imagined."
"And you think this teacher is Akira?"
"I think she's connected to whatever's happening in my dreams. Whether those dreams are memories, visions, or something else entirely." Nezuko's grip on his hands tightened. "But I know she's dangerous. My instincts are screaming warnings every time I see her."
"Then we need help. Someone with more resources and experience than either of us has."
"Who could we trust with something like this?"
"Tengen gave me a way to contact him in emergencies. This qualifies."
---
Alone in his quarters, Tanjiro examined the communication package from his previous encounter with Tengen. Using it represented a point of no return. The small wrapped bundle felt heavy with implications—once he sent that signal, he'd be committing to investigating a fellow Hashira based on suspicions and dream testimonies.
"If I'm wrong about this, I'll have betrayed a fellow Hashira's trust," he murmured to himself, weighing the package in his palms. "But if I'm right..."
The sound of Akira's voice drifted from the courtyard below, discussing mission logistics with other Corps members in perfectly professional tones that made her sound like the ideal colleague.
"If I'm right, then Nezuko is in immediate danger, and I'm the only one who knows it."
His enhanced senses caught that same subtle wrongness in Akira's scent even from this distance—too controlled, too clean, like someone masking their true nature through artificial means.
"Tengen will know what to do. He'll have resources I don't, connections I can't access."
Tanjiro opened the communication package with steady hands, revealing coded materials that looked innocuous but carried urgent meaning for those trained to read them.
"I hope I'm wrong," he whispered as he prepared the discrete signal that would summon help. "But I can't risk being right and doing nothing."
Outside his window, Akira's laughter carried on the evening breeze—warm, charming, and absolutely terrifying in its calculated perfection. Someone who could laugh with such apparent joy while potentially threatening everything he cared about represented a level of deception that chilled him to the bone.
"Nezuko's safety matters more than my career." He activated the signal with firm resolve. "More than protocol. More than anything else in the world."
The die was cast. Within hours, Tengen would receive the message and understand that something dangerous was happening at Corps headquarters. Something that required immediate investigation by someone with resources and experience beyond Tanjiro's current capabilities.
"Please let this be the right choice," he prayed to whatever forces might be listening. "And please let us discover the truth before anyone gets hurt."
The communication package dissolved into ash after sending its encoded message, leaving no trace of what he'd done. But the weight of the decision remained, heavy with the knowledge that he'd just set events in motion that couldn't be undone.
In the courtyard below, Akira's voice continued its cheerful discussion of tomorrow's mission plans, completely unaware that her time as an unknown threat was rapidly coming to an end.