"You want to give a nichirin blade to a demon?"
Sakonji had seen many facial expressions on Giyu's face and the furrowed brows and downturned lips was an old favorite. From smell he knew that the boy was conflicted and he could guess at his thoughts–unwilling to question his master, unwilling to make a demon stronger, and unwilling to put any of them in danger if something did go wrong. Giyu had been willing to take a risk on Tanjiro being peaceful as long as he remained unprovoked, but it was something quite different to put a sword in his hand.
But after watching Tanjiro perform the hinokami kagura with a wooden sword at various points throughout the dance, Sakonji was certain that he was one of the demons capable of using breaths. He'd never once met a demon who could do it and didn't know any demon slayer who could actually claim such a thing, but the stories about it ran rampant. Demons like that were incredibly strong.
He hadn't lived to old age by being careless, so he had requested something useless but believable from Giyu so the boy would come up and visit them. Sakonji was certain that he could take Tanjiro if he lost control, but it was always better to be cautious. And it had been ever so amusing to watch Tanjiro glare at Giyu from the corner of the hut. Nezuko had done her best to try and hide the fact that Tanjiro obviously remembered and disliked Giyu, but the occasional growl whenever he had moved too close to her had been unmistakable.
Tanjiro just stared at the sword when Sakonji offered it to him. His expression was almost identical to the one Giyu was wearing, though it was hard to tell if Tanjiro was frowning because of the bamboo in his mouth. Nezuko stepped closer and took the hilt of the sword from him and within seconds Tanjiro had taken it from her.
"Do the hinokami kagura, Tanjiro." Nezuko looked a bit smug that she'd gotten her brother to do what she wanted so easily, and she smelled as fond as ever of his overprotectiveness. "Use the sword."
He listened to Nezuko right away like he always did. Tanjiro moved a few feet away from all of them and then started up the hinokami kagura, his face at ease and movements certain. There was never a noticeable difference in his movements, but a heady scent of strength and danger started to waft off him with each swing of his sword. Tanjiro performed two slashes and his hands lit on fire with a dark pink flame, the sword following soon after.
Another, stronger smell suddenly covered up Tanjiro's. Nezuko was terrified and Sakonji realized there had been an oversight, because he had forgotten to explain his thoughts on Tanjiro's abilities to her. He had simply told her that the burnt training swords were nothing bad, and it seemed Tanjiro had either stopped his power on his own or been incapable of continuing without a proper medium because he hadn't burnt the training swords every time and she'd never seen him light on fire before.
Nezuko whipped off her haori and raced to Tanjiro as he did a circular slash. She was slower than both Sakonji and Giyu still, but when Tanjiro's blade cut through the air fire followed, shooting outwards and stopping Giyu from moving to catch Nezuko. All of her fear was for Tanjiro in that moment and she showed no consideration for herself, ducking a swing of the flaming sword as Tanjiro failed to notice her in time to stop. She shoved her haori against his hands and made a patting motion with it.
Sakonji had long since realized that she was an idiot when it came to her brother, but watching her try to smother the flames on Tanjiro's hands with clothing really cemented it. The fire spread to her almost instantly, growing and engulfing them both.
"Nezuko!" Sakonji exclaimed.
Giyu sounded just as panicked, "Kamado-chan!"
He about had a heart attack, but then he realized that Nezuko wasn't screaming nor did she appear to be getting hurt at all. She and Tanjiro were unscathed by the supernatural fire.
"I'm okay," Nezuko called.
And then she embraced Tanjiro, and the fire grew larger and brighter. Sakonji was torn between deep relief and irritation for the scare, but he acknowledged it was his own fault for not explaining things properly to his student and so he kept his mouth shut. He joined Giyu over at the tree that had been hit by Tanjiro's circular slash, examining the damage that had been done to it. There was a burn mark on the bark but the fire hadn't spread at all from the initial point of contact.
It seemed like Tanjiro was capable of controlling the flame quite well, which meant Nezuko's missing haori had been burnt on purpose. After how he had reacted to seeing Giyu again, Sakonji could guess why it had met such a terrible fate, but that didn't make him any happier. He'd spent hours on the damned thing.