The Demon's Apprentice || Rewrite

Testing

A few weeks after the incident with Douma passed, following the same stable routine.

And with each day and training session, Tanjirou's strenght only grew. The boy's stamina improved, he could endure much more for longer, and of course, with each success, Tanjirou's excitement grew.

One day after a rather long lesson, Tanjirou was sitting in a seiza position staring at his hand. The boy had recieved a minor cut during the lesson, but it had healed quickly.

Kokushibo had observed Tanjirou from a distance. He could tell that the boy was contemplating something, perhaps reflecting on the session and the improvements he had made.

Seeing the minor cut on Tanjirou's hand, Kokushibo's gaze softened slightly. It was a subtle reminder of the fragility that came with being a living, breathing being. He approached Tanjirou silently, standing a few feet away from the boy.

Tanjirou stared at his palm silently before digging his nails into the skin. Deep red blood dripped down his wrist and onto the floor, and Tanjirou watched with intrique in his eyes.

Kokushibo's eyes widened in alarm. He was taken aback by Tanjirou's actions, his usual composure slipping somewhat.

"Tanjirou." He said with a hint of warning in his voice. Kokushibo closed the distance between them and crouched down to Tanjirou's level. He grabbed the boy's hand, gently but firmly, preventing him from causing further damage.

Tanjirou blinked up at Kokushibo, a mix of confusion and curiosity in his expression. "It'll heal."

Kokushibo's grip on Tanjirou's hand tightened slightly, a stern expression on his face.

"It's not... about whether... it will... heal or not." Kokushibo said firmly. "It's about... why you are... doing this... in the... first place."

Kokushibo's voice was serious, and his eyes searched Tanjirou's expression for any indication of an explanation. He wanted to understand what was going through the boy's head.

"I'm testing something." Tanjirou answered and turned to look at the few droplets of his blood on the floor, his wrist still in Kokushibo's hold.

Kokushibo followed Tanjirou's gaze towards the droplets of blood on the floor. His grip on the boy's wrist didn't loosen, and he kept a careful eye on him.

"Testing what?" He asked, his tone still firm, but with a hint of concern.

"A while back I did that thing, setting my blood on fire. You said that it was my Blood Demon Art." Tanjirou answered. "I'm trying to figure out how I did that."

So this is what the boy was trying to figure out. Kokushibo recalled the instance when Tanjirou had inadvertently used his Blood Demon Art. It had been an unexpected and brief moment during a training session, and neither of them were entirely sure how the boy had summoned the fire.

Kokushibo relaxed his grip slightly, his stern expression softening a bit. He understood Tanjirou's curiosity.

"And trying... to hurt... yourself is... supposed to... make you... figure it out?"

"I figured that since it was my blood that erupted into flames back then, it might be the best place to start, since it's something I've technically done before." Tanjirou explained.

"And I didn't know any other way to acquire my blood, so cutting a small cut was kind of all I could think of." Tanjirou mumbled, clearly feeling bad for causing Kokushibo confusion, and concern.

Kokushibo took a moment to process Tanjirou's explanation. He could see the logic in the boy's thinking, but he couldn't deny the worry he felt upon seeing the boy's wound. Despite being a demon now, Kokushibo still instinctively treated Tanjirou like a human.