Senjuro's age: 10

Senjuro's arms burned as he swung his wooden practice sword again and again. He had to get better, stronger, faster; he had to become a Demon Slayer. For centuries, the Rengoku family had mastered the art of Flame Breathing and used it to kill demons. He couldn't be the one to break that chain now. He needed to learn Flame Breathing so that, when Kyojuro became a Hashira, he could be Kyojuro's tsuguko. That way they'd continue the family tradition.

Part of mastering Flame Breathing was to get his nichirin sword to change colors. But after training for almost two years, the steel was the same silver it had been when he'd first received it.

He was a failure. He was failing Father, who'd first taught him the basics of wielding a katana, and he was failing Kyojuro, who'd picked up his training since Father had stopped. And he was failing each and every one of the past Flame Hashira - the entire Rengoku line.

With a cry that was half-groan, half-sob, he dropped the practice sword, falling to his knees after it. This was hopeless. He was never going to learn Flame Breathing, or get his nichirin to change colors, or be a Demon Slayer, or protect people, or do anything worthy of note in his life. All he could do was make sure the house stayed in decent shape and that Father didn't drink himself to death while Kyojuro was out on missions.

He knelt on the ground for a while, unable to see much point in moving. Eventually, he heard the sound of approaching footsteps, and a pair of sandal-clad feet appeared in his field of view.

"Senjuro!" Kyojuro greeted him as if all was right in the world.

But it wasn't, because Senjuro was going to be the first blemish on several hundred years' worth of family history. He couldn't bring himself to meet his brother's eyes.

"What's wrong?" Kyojuro asked, crouching to be at eye level with him.

Senjuro continued to avoid his gaze. Though they both knew of his inability to learn Flame Breathing, he didn't want to give voice to his failures. It would make real the fact that he could not carry on their family line.

"You were training, I see!" Kyojuro observed. "Are you having trouble?"

Wordlessly, Senjuro nodded.

"Would it help if I watch you and advise you on how to improve?" Kyojuro offered.

He shrugged. It probably wouldn't. No matter how long he practiced, the forms never came naturally to him the way they did to Kyojuro and, in the past, Father. He lacked the fluidity, the ability to move with the forms rather than just taking the correct positions. The katana never became a part of him the way it seemed to for his brother.

"Well, let's give it a try!" Kyojuro held out a hand.

Senjuro didn't take it.

"Come on, Little Flame!" he encouraged. "If you want to become a Demon Slayer, don't give up now! Keep trying and you'll get there someday soon!"

Deep down, in his heart of hearts, Senjuro wasn't sure he even wanted to become a Demon Slayer. It was just the path that had been set for him at birth; he'd never bothered to question it. But clearly he wasn't cut out to join the Corps.

Kyojuro tilted his head, studying Senjuro with those piercing gold-and-red eyes of his. They were the eyes every Rengoku had, a marker of the heritage he could never live up to. "If you don't want to become a swordsman, that's okay too," Kyojuro said, his voice uncharacteristically soft. "You should follow whatever path feels right to you, Senjuro, no matter what anyone else thinks."

"But the family line—"

"Your happiness matters just as much as our lineage," he declared, "if not more! I'll always support you no matter what you choose!" He rested his hands on Senjuro's shoulders and gently squeezed.

Senjuro finally managed to meet his gaze. Seeing the total conviction in his big brother's eyes made him hope, just a little, that he really could find the right path for himself in life. No matter how long it might take or how hard it might be, Kyojuro would always be there to support him.

But at the same time, he had to keep trying to become a Demon Slayer. He couldn't turn his back on so many years of history, on all of the blood that had been shed during the war against demons. He couldn't shake the feeling that he owed it to his ancestors not to give up. Maybe this would be the last push he needed to finally figure out Flame Breathing.

He tried to ignore the part of him that knew it wouldn't happen. He wasn't meant to wield Flame Breathing. He probably wasn't meant to wield any Breathing technique, no matter how many he tried. But in spite of knowing this, he couldn't help but wish he would someday prove himself wrong; that one day, he'd be Kyojuro's tsuguko. It was like Kyojuro said: he couldn't give up now. He wasn't sure he'd be able to face himself if he did.

So he took a deep breath and requested, "Can you walk me through the first form again, please?"

If Kyojuro thought anything was off about Senjuro's decision to resume training, he gave no indication of it. He simply smiled and exclaimed, "Of course, Little Flame!" He offered Senjuro a hand up again, and this time, Senjuro took it.

Little Flame. The nickname was a reminder that flames were in his blood. He just had to keep trying again and again until he mastered that fire.