A Split in The River of Time

Part 1: The split

(This is my first time posting one of my stories to any kind of website, so be gentle I beg :D I have a lot of this story done,  so I will post maybe twice a week? maybe more depending on if people like it and depending how much I end up writing per week)
(Italics means characters thoughts or breathing techniques, Other normal stuff)

"-san" The unusual amount of noise in the forest hurt Giyuu's ears. Like a constant buzzing, or ringing, for some reason in the middle of the woods.

"yuu-san!" His brain began to process the events unfolding in front of him.

"GIYUU-SAN!" Tanjiro shouted again, causing Giyuu to blink away his delirium. A searing pain ran through his body, and he looked to the source of pain. His left arm, or what was left of it, was definitely the cause as from just above the elbow down, his arm was missing. He began a breathing technique before the pain spread and left him imobile, and he clutched his sword in his right hand. He had arrived late, and this demon had killed the flame pillar, Kyojuro Rengoku. The monsterous demon, Upper moon 3, looked back towards Giyuu with a fanged-grin.

"You aren't as easy as Kyojuro to kill, I suppose. Even after I've started to use my Blood demon art, you've been keeping up." Akaza dropped the slayers' severed arm to the ground as he regrew several parts of his body. An arm, a leg, massive parts of his torso reconnected and regenerated.
"Do you still want to fight me, Pillar? If you become a demon, you won't die like Kyojuro over there. That arm would grow back right away like mine!" he said, his grin widening as he gestured to the barely breathing fire pillar.

"How exciting, however. It's been years since I've met a water pillar of this strength!" He continued, puffing his chest out. Giyuu put his foot behind him, and gripped his sword even tighter. If he had let go of it for even a millisecond, he wouldn't be able to grip it again. He, Tanjiro, his sister, the boar headed kid and the lightning breath kid would die. With a brief exhale, and a maniacal laugh from Akaza, The two clashed again. Tomioka was weakened, certainly, but he was able to keep his sword intact and between him and the demon for the moment. When Akaza began releasing his techniques, Giyuu realized how difficult performing his styles would be with one arm as he tried to use dead calm to deflect the attacks. Luck was on the side of the water pillar however, and midway through the barrage, Akaza faltered. He grit his teeth and lunged at the water pillar one more time but his attack was stopped as a water breathing form came out and cleaved his fist off right before it landed its mark on his chest. The demon realized this was a lost cause and simply ran with the death of one pillar under his belt as the sun rose only half a minute after he was in the treeline. Giyuu stood beside the body of the former flame hashira, his Mismatched Haori bloodstained and his arm bleeding profusely. Tanjiro ran towards the treeline and threw his sword as hard as he could into the back of the quickly retreating demon, while Inosuke ran towards the water and fire pillar. As Tanjiro's rage and tirade of insults and yelling subsided he ran to an injured Giyuu and Kyojuro's body, and as soon as he approached them, Giyuu's sword fell to the ground and the man fell to his knees.

"Giyuu-san, Rengoku-san!" Tanjiro said with tears in his eyes. He dropped to the ground beside the pillar, crying as he held onto Kyojuro and Giyuu's haori's. That was all Giyuu remembered happening, before he passed out.

"Tomioka?" The voice pierced through his cloudly and thought filled head.
"Tomioka-san?" Shinobu said cautiously. Giyuu's eyes fluttered awake, and he bolted forward despite his body begging him to be more careful. He looked around the room, only for a hand to be placed on his shoulder.
"Please, lay back down. You need to rest more, Tomioka." He peered up to her face, and saw genuine concern written on her face for once. He tried to push her hand off of him, but all that moved was the limited amount of arm he had left on that side. He swears he heard Shinobu stifle a giggle, but she kept face.
"You can't use that arm anymore, Tomioka-san." Her face wasn't as depressed now, but the smile she wore was still accompanied by a sad face. He didn't like this look on her, it made him feel weaker than usual for some reason. Without warning, she suddenly stood and reached to pat her haori flat, before her eyes began to linger on Giyuu and his injuries. She sighed, and with a slight pause, she continued.
"I'm going to be honest with you... you may need to retire, Tomioka-san." she said, the words felt like poison as they entered his ears. Retire? The word alone made Giyuu's blood heat up slightly.

"I can't do that Kocho." he replied deadpan. She motioned towards his armless side, arguing back.
"You have one arm, Giyuu. You certainly cannot fight any Upper rank demons in this state, and I would even argue that you need to prove your abilities as a Hashira all over again!" Her voice began to get louder, and her face twisted in annoyance and sadness. Why was she so concerned over this? They were demon slayers afterall and the conversation had just started but she was already yelling.
"If that's what it takes, I will." She seemingly pouted. Giyuu's eyes drifted back down to his missing limb, and he could feel the realization begin to set in. Shinobu saw his eyes widen, and She leaned back over to his side to help comfort him, just as Giyuu started to hyperventilate.
"I'm missing an arm." He said through heavy breaths. He was missing an arm, and now all his training was useless.

I wasn't capable of being a Hashira with two arms, how would I keep this title with one? How would I slay demons? Could I even continue being a slayer? Would I really have to retire like Kocho said?  Questions swarmed through his mind and left him clutching his chest and his total concentration breathing failing, causing even more stress on his body.
"Tomioka?" Shinobu said, her voice falling on deaf ears.
"Giyuu!" She shouted, which caught his attention. He looked at her, and he could feel the overwhelming doubt shrivel a small bit. He looked into her eyes, eyes which normally held a fake expression and saw genuine concern.

"Tomioka, I understand that you feel like you need to continue but I really do advise against it. If you have no issue, I will be sending out a crow detailing your retirement. You can go to the Ubayashiki mansion yourself in a couple days." Giyuu looked away from her quickly. He couldn't go into retirement simply because of a lost limb. Whether or not he was weaker without an arm, he was still a strong slayer. Right? He wasn't very confident, but he hadn't planned to live after being a slayer. He was going to live and die a slayer, just like him. Giyuu didn't think it was fair that some slayers got to retire and some died protecting people. So he opened his mouth and spoke.