The moon hung high above Mitsuri's mansion, casting soft white light across the wooden courtyard. Crickets sang, and the sweet scent of honey lingered in the air.
Tanjiro and Jinwoo stood near the gate, bags packed. It was time for the next Hashira training.
Mitsuri hugged Tanjiro first — tightly, warmly.
"I'm so proud of you, Tanjiro! You improved so much!"
Tanjiro blushed, waving his hands. "N–no, I still have a long way to go!"
Then she turned to Jinwoo.
Her bright smile softened… almost shy.
"Jinwoo… thank you for trying so hard. And… I'm glad you liked my pancakes."
There was no joke this time, no exaggeration — just genuine emotion.
Jinwoo nodded. "They were delicious."
Mitsuri's eyes sparkled. For a moment she looked like she might explode from happiness — but she kept it composed and waved goodbye.
"Stay safe! Both of you!"
Tanjiro waved back energetically. Jinwoo gave a small bow — subtle, but respectful.
MEANWHILE
A crow swooped down from the sky, landing on the wooden beam of Obanai's mansion.
Kaburamaru lifted its head as Obanai extended his arm, and the crow dropped a small envelope sealed with a flower symbol.
A letter from Mitsuri.
Obanai opened it silently.
"Obanai~! Tanjiro has improved so, so much! I'm so proud of him!"
"And we also have someone new here! His name is Sung Jinwoo!"
"He trains super seriously and he's very polite! I think you would like him too!"
— Mitsuri 💕
Mitsuri's handwriting was bubbly and full of warmth.
Obanai stared at the words much longer than necessary.
Not because of the request.
But because of that one simple line: "Take care of yourself."
No one else ever said that to him.
His grip tightened slightly — not on the paper, but on his emotions.
Then he reached the bottom of the letter and stopped.
Because there — in small handwriting — was one more line Mitsuri had added:
> "— and Tanjiro and Jinwoo san really loved my pancakes!"
That single sentence changed everything.
Obanai didn't get angry.
He didn't shout.
He didn't tear the letter.
He just looked down, eyes shadowed under his bangs.
"…Pancakes. She cooked for him?"
Kaburamaru gave a soft hiss — sympathetic, like it understood the pain.
Obanai folded the letter carefully and kept it inside his robe — not discarded, but treasured.
Then he walked toward the main hall to prepare the training grounds.
The gentle tone in his voice from a moment ago was gone.
Now it was cold… sharp… competitive.
ARRIVAL — THE SERPENT MANSION
When Tanjiro and Jinwoo reached Obanai's mansion, the air shifted.
The training field was narrow, dark, and silent — unlike Tengen's joyful one, or Mitsuri's lively pink atmosphere.
The only light came from paper lanterns shaped like serpents.
Tanjiro swallowed nervously. Jinwoo simply observed.
Footsteps tapped against wood.
Obanai emerged from the shadows, eyes cold behind his bandages.
"You arrived early."
Tanjiro bowed immediately. "Thank you for having us!"
Jinwoo nodded politely.
Obanai didn't return the greeting — he simply stared at Jinwoo for a few seconds too long.
Not fear. Not respect. Not recognition.
Jealousy.
It wasn't hidden at all.
Kaburamaru stared too, tongue flicking aggressively — sensing Obanai's emotions.
Finally, Obanai spoke in a low voice:
"…So you're Jinwoo."
Jinwoo met his gaze. "Yes."
Obanai stepped closer — almost nose to nose.
"Do not misunderstand anything."
Tanjiro flinched.
Obanai's voice stayed calm… but sharp like a blade:
"Mitsuri is a very precious person. To me."
He wasn't threatening Jinwoo physically — he was warning him emotionally.
"Stay respectful. And don't make her cry."
Jinwoo didn't back away.
"I don't hurt people who are kind."
Obanai held his gaze for 3 full seconds.
Then Obanai turned away.
"Training will begin tonight. No dinner break. No rest."
Tanjiro: "Tonight?!"
Jinwoo: "That's fine."
Tanjiro stared at him. "How are you not tired… from all this training?"
Jinwoo didn't answer. He didn't know how to explain that his body barely registered fatigue anymore — like the training was only warm-up.
FIRST TRAINING — STABILITY
Several demon slayers kneeled in a line, trying to balance on wooden poles while Obanai walked among them.
Anyone who wobbled got tapped on the shoulder — and forced to start over.
Tanjiro trembled, trying to stay balanced. Jinwoo stood perfectly still.
Some demon slayers whispered:
"Look at him…" "He's not shaking at all." "Is he even human?"
Tanjiro felt pressure, but he also felt motivation.
"If Jinwoo can do it… so can I!"
He steadied himself, adjusting his breathing.
Obanai passed by, glancing at Tanjiro. No compliments — but his pace slowed slightly.
That was praise in Obanai's language.
BREAK? NO BREAK.
Hours later, sweat covered every demon slayer except one.
Jinwoo.
Tanjiro leaned forward, exhausted — but still standing.
Obanai approached silently. "Not bad. But you're still slow."
He wasn't talking to Jinwoo — he was looking at Tanjiro.
Tanjiro nodded firmly. "I'll improve."
Obanai's eyes moved to Jinwoo.
"…And you."
Jinwoo looked back without blinking.
"I don't understand you. I don't know what you want. And I don't trust people like that."
There was no hatred — just a wall.
Tanjiro opened his mouth to defend Jinwoo — but Jinwoo placed a hand on his shoulder.
"It's fine."
Obanai clicked his tongue and turned.
But Jinwoo's system had already activated.
> System Scan — Target: Obanai Iguro
Honor level: High
Traits: Loyal • Devoted • Self-sacrificing • Jealous nature
Jinwoo exhaled quietly.
So this man is rough, but not evil.
He didn't care about Obanai's words — he cared about the truth of the heart.
A shadow emerged silently behind Jinwoo — an ant king soldier shadow unit — swift and elusive.
Without anyone seeing, it slipped into Obanai's shadow.
> Shadow Assignment: Obanai Iguro — done.
Jinwoo smirked.
"You care about Mitsuri more than you show."
Obanai froze — like someone had read the deepest part of him.
"What did you just say?"
Jinwoo looked away. "Nothing."
Obanai didn't speak for a few seconds — but there was a storm behind his eyes.
---
NIGHT CONVERSATION
After training ended, before sleep, Tanjiro and Jinwoo sat near the balcony.
Lantern light flickered against the floor. Outside, fireflies danced in the dark garden.
Tanjiro broke the silence.
"Obanai… really cares about Mitsuri, doesn't he?"
Jinwoo nodded. "A lot."
"He just doesn't know how to express it?"
"Exactly."
Tanjiro smiled softly. "I think that's… kind of sweet."
Jinwoo didn't respond — but his expression softened.
Tanjiro turned to Jinwoo again.
"Hey… why do you help us? You're so strong. You could do everything alone."
Jinwoo looked up at the moon.
"…Because power without purpose is useless."
Tanjiro blinked.
"Back home… I lost a lot. I don't want to lose anything again."
Tanjiro felt those words hit hard — because he understood them.
He nodded.
"I'll protect Nezuko. And you'll protect everyone else. Together."
For Jinwoo… it was the first time in years someone talked to him like an equal, not a weapon.
That mattered.
Obanai stood on the other side of the paper door, listening to their conversation without meaning to.
He didn't open the door.
He didn't interrupt.
He simply whispered to himself:
"…Tanjiro is good for Mitsuri. But you…"
He stared straight ahead — toward Jinwoo.
"…I still don't know what you are."
Kaburamaru hissed again.
And training was not over yet.