After four whole days of nothing but intense training, the three Demon Slayers were summoned to investigate the Mugen Train, which was currently inside a train warehouse. On a dark and cloud night, after stopping at a noodle shop and railway bureau-where they received over two dozen bento boxes. Natsu Rengoku, Kyojuro Rengoku and Inosuke Hashibara stood side-by-side as they gazed at the Mugen Train.
"So, this is the Mugen Train." Natsu smiled as he read the sign, "Mugen" on it.
"Yes. There is supposed to be a demon possessing this train, once it starts moving." Kyojuro smiled. "Though the faint trace of a demon remains."
Natsu looked at Kyojuro as if he wanted ask him something. "Bro, do you think the demon will come out when the train start moving?"
"Only time will tell. If the demon does appear now or when the Mugen Train starts moving, we'll be sure to eliminate it." Kyojuro smiled, brightly.
Natsu saw Kyojuro's bright smile and it made him feel a bit more energetic. "Right! As soon as the demon shows up, we'll be sure to-" Before Natsu could finish his sentence, Inosuke had quickly ran and headbutted the front head of the Mugen Train. Causing a loud thud heard all around the train shed.
Inosuke then pulled out his dual Nichirin swords. "Come out, demon! I know you're hiding in there! I can't wait to put cut your head off!" Inosuke shouted and pointed one of his Nichirin swords at the Mugen Train.
Natsu paused as he watched Inosuke shout and challenge the train.
Kyojuro kept smiling.
"Hey! Who's causing that racket over there?" Suddenly a common man who works on trains had walked around the train and noticed Kyojuro Rengoku, Natsu Rengoku and Inosuke Hashibara. "What are you three doing? This place is off-limits!" The man warned the three Demon Slayers.
Inosuke glanced at the train worker and quickly assumed that he was the demon. "If this place is off-limits, then..." Inosuke pointed one of his Nichirin swords at the train worker. "You must be the demon controlling this train!"
The train worker gasped. "A demon? What in the hell are you talking about?"
Natsu gasped as he knew what Inosuke was about to do.
"You can't fool me, demon!" Inosuke took a dual sword stance, then attempted to charge at the train worker. "I got you where I wa-" Inosuke then grunted as he found himself caught within a full nelson lock.
"No, Inosuke! He's not a demon! He's a human who works on trains!" Natsu told Inosuke while restraining him.
"Ah, come on!" Inosuke grunted as he attempted to break free from Natsu's grapple.
"Is there a problem? If so, then I can alert the police and-"
"No! Everything's under control, mister! We came all from the Railway Bureau to deliver the bento boxes." Natsu felt a bit embarrassed and told the train worker, while restraining Inosuke in a full nelson.
"Oh? Why didn't you say so?" The man then called upon his co-workers. "Hey, everyone! They brought us bento!"
Five Minutes Later
Many train workers who worked on trains most of the day were eating bento boxes, while Natsu was keeping watch of Inosuke who was outside of the train warehouse.
Inosuke sat down on the dirt, pouting and mumbling. "Tch. Why the hell do they get to eat those delicious boxes, while I sit here on the dirt?" Inosuke muttered as an irritated vein appeared on his right forehead.
"Because Inosuke, the food is theirs. Those train workers worked hard all day to make and fix these trains. They deserve to eat just as much as us." Natsu explained.
"Yeah, well whatever. I still deserve to at least try one of those delicious bento box." Inosuke mumbled again.
"We already been through this. If you eat one bento box, than you'll end up eating everyone's bento box. Also, we already ate ramen today and you had six bowls." Natsu added.
"So? Those ramen bowls weren't even close to filling my appetite!" Inosuke said while pounding his chest.
Natsu chuckled. "I'm sure they weren't."
Meanwhile, Kyojuro was speaking with one of the other train workers.
"So, why was the Mugen Train brought here?" Kyojuro asked.
The other train worker begun to explain to Kyojuro as he looked at the Mugen Train. "There is nothing wrong with the body, but... word on the street is that it is a man-eating train. You don't know how bitter this makes us feel. So now it's being put back into service. We want to do all we can to put her back into shape and send her back out into the world."
"Hm? Back in service?" Kyojuro asked.
"Yeah. Tomorrow night. That's why we're all here." The other train worker explained.
Suddenly, Kyojuro had felt a bad aroma within the train warehouse and ran toward the demon scent.
"Demon! There's a demon here! Caw!" Kyojuro's crow yelled.
Kyojuro ran until, he saw a boy cowering of what or who was in front of him. Kyojuro then looked into the boy's direction and spotted a bald gray-skinned demon with blue rectangle-like tattoos all across his body. His sclera was black and his snake eyes were yellow. The demon had worn a sleeveless blue Gi, dark brown pants and dark brown shoes. His name Hayai.
Kyojuro partially opened his Nichirin sword, which caused Hayai to reveal that he has a boy named Tatsu as a hostage, with sharp fingernails had already pierced his outer flesh.
"Tatsu!" One of the train workers yelled as he arrived.
"All of you, stay back!" Kyojuro ordered.
"Chief!" Tatsu yelled.
"You bastard." The Hayai yelled.
"Let the boy go!" Kyojuro demanded that Tatsu be released.
Hayai scoffed. "How arrogant..."
Meanwhile, Natsu still kept watch over Inosuke outside of the train warehouse.
"Listen, Inosuke. All I'm saying is that you be a little bit courteous of other-" Natsu stopped himself as he and Inosuke felt a bad aroma coming from the train warehouse. "Inosuke. Something tells me... that there's a demon nearby." Natsu looked at the train warehouse and stared at it. 'That demon must be hiding in that warehouse.'
Inosuke jumped onto his feet and as he can sense the demon, too. He then drew out his dual Nichirin swords. "Yeah. Let's get him!"
"Wait!" Natsu stopped Inosuke from running into the station.
"What now?" Inosuke had grown a bit impatient and irritated.
"Let's go around. We'll catch it by surprised." Natsu smiled, then started running towards the rear of the train warehouse.
Inosuke silently agreed, then followed Natsu to the rear of the train warehouse.
As they had successfully made it to the rear of the train warehouse, they hid behind glass windows and started hearing the conversations between Kyojuro had with the demon named Hayai. They could easily hear through the glass windows.
"Looks like you can't kill me without harming this kid, eh?" Hayai asked, then smirked in front of Kyojuro.
"Help me..." Tatsu silently pleaded as Hayai kept his sharp fingertips in Tatsu's chest, causing him to bleed out a bit.
"Don't worry! I will save you no matter what happens!" Kyojuro told a threatened and injured Tatsu.
'I can hear bro's voice and two others. The one that's asking bro to help must be held hostage or threatened. And the one that sounds sadistic must be a demon.' Natsu thought as he could hear their conversation.
Hayai growled. "Not on your life. Just yesterday, I slashed a woman in the middle of the street until I got bored and left."
Natsu silently gasped after hearing that confession. 'So, the woman that me, bro and Inosuke had found on the road... the one barely clinging to life. It was him who did that!'
Flashback
During the previous night the Demon Slayers such as Kyojuro Rengoku, Natsu Rengoku, Inosuke Hashibara and a member of the Kakushi were in a small village and had followed a trail of screams coming from a woman. It had taken them a full minute, until they found a woman lying unconscious on the middle of the road. The woman wore a green haori and had multiple cuts on her flesh to where she bled out, but none of her injuries were life threatening.
Natsu froze in traumatization as he stared at the woman's unconscious body.
Kyojuro checked her pulse on her neck. It was faint, but not weak enough to disappear. "She's alive!"
Natsu suddenly snapped out of traumatization after confirming that the woman was still breathing.
"Her wounds need to be treated right away!" The female Kakushi informed Kyojuro.
Kyojuro nodded, then looked toward Inosuke. "Inosuke. Use your Spatial Awareness ability to locate any nearby demons!"
"You got it!" Inosuke gave Kyojuro a thumbs up, then planted his dual Nichirin swords into the dirt. 'Beast Breathing! Seventh Form...' Inosuke then utilized his senses and created a large radius bubble within the small town for thirty seconds.
"Did you find anything?" Kyojuro asked Inosuke.
Inosuke took his dual Nichirin swords out of the dirt. "No. He's gone! Dammit!" He felt sour as he urged to kill the demon.
A group of Kakushi then came with a paper stretcher to carry the unconscious woman to safety. Natsu watched as the group had done their work and couldn't help but feel pity for the woman.
End Flashback
"Even if she does survive, she's doomed to be consumed by fear for the rest of her life." Hayai said.
Natsu heard what the demon Hayai said from the outside and started to feel angry.
"I won't let you. We're going to treat her mental and verbal wounds as long as it take!" Kyojuro replied.
Hayai stared at Kyojuro for a second, then laughed. "I'll show you what that self-righteous attitude of yours a thing or two. Once I find that woman, again-or any woman... I'm going to kill them and leave their corpses to rot!" Hayai laughed.
Natsu growled. Not loud enough for Kyojuro and Hayai to hear him from the inside. He clinched his right fist out in frustration after hearing Hayai's sadistic plan.
Inosuke slightly looked at Natsu, who seemed to be visibly getting angry. 'What's his deal?'
"We kept her hidden. You will never find her-nor will we let you harm anyone else!" Kyojuro replied to Hayai.
Hayai suddenly looked at the bento box that he stomped on, then thought of something. "That bento box came from the Railway Bureau, right?"
"And what of it?" Kyojuro asked.
"There's an old lady and her granddaughter who work there for a living. Maybe I'll go over there and smash their bento boxes after I kill them." Hayai smirked in front of Kyojuro.
Natsu suddenly thought of Tomi, the elderly woman and her granddaughter, Fuku. The bento vendors. 'Is he really gonna go after them?' Natsu thought to himself.
"They have nothing to do with me." Kyojuro told Hayai.
"But you know them, right?" Hayai asked, then looked at the bento box. "Those are stationed bento, right? I can find out where you got them."
Kyojuro took a step forward.
"Don't move or this kid dies!" Hayai held Tatsu closer to him, pressing his fingertips deeper into his chest. "My fingertips are two inches away from puncturing his heart. If you want him to live, you're gonna let me go, right now!" Hayai threatened Kyojuro.
Kyojuro frowned.
"Also, if you want to save that old woman and her granddaughter at the station, then you have to get there before I do." Hayai then focused on Tatsu, whom he's threating to murder. "Bur first, I change my mind. I think I'll kill this kid right now!"
Kyojuro frowned, then gripped his hilt.
One Second Later
Suddenly, a redhead kid dressed in a fiery haori jumped through the glass window toward him.
"Natsu." Kyojuro called.
"Tch!" Hayai froze as he saw Natsu Rengoku for the first time. 'I get it. This smiling idiot had backup this whole time!'
"How dare hurt innocent people!" Natsu yelled, as he ran toward Hayai and tried to slash him with his Nichirin sword.
Hayai thought quick and decided to use Tatsu as a human shield by removing his fingertips from Tatsu's chest then held him in front of Natsu like a shield. "Think fast!"
Natsu stopped as he saw an injured Tatsu in front of him. Then witnessed Tatsu being thrown high in the air like an adamant object. 'He threw him in the air...' Natsu thought.
Suddenly, Hayai had teleported behind Natsu. "Made you look!"
Natsu gasped as he then realized Hayai had suddenly teleported behind him. 'He's fast!' As he tried to react and turn his body around to encounter Hayai, Hayai quickly folded his sharp fingers and attempted to pierce Natsu through the heart. But before his fingers could touch Natsu's chest, both his hands were severed by Kyojuro Rengoku.
"Bro!" Natsu chanted.
"We're not done, yet, Natsu!" Kyojuro said.
"Right!" Natsu smiled and nodded.
Hayai jumped a few yards away from Kyojuro and Natsu, who were standing side-by-side and were ready to fight him. "So, you had a brother waiting to ambush me, eh?" Hayai stared at Kyojuro. "Heh." Hayai chuckled. Well, let's see how fast you can keep up!" As soon as Hayai turned away from Kyojuro and Natsu, he was met a pair of Nichirin swords quickly slashing off his arms lower waist by Inosuke Hashibara.
"Gotcha!" Inosuke said after slashing Hayai in half, horizontally. Inosuke had snuck into the warehouse without Hayai's knowledge as Natsu kept him busy for half a minute.
"Wh-what? When did you-"
"I got 'em, guys!" Inosuke yelled as he grabbed and held Hayai by the back of his neck and held him like a human shield in front of Natsu and Kyojuro.
"Good work, Inosuke! Now keep him still!" Kyojuro told Inosuke.
"You got it!" Inosuke said as he kept him in place off the ground, facing Kyojuro and Natsu.
"Wait, no! This can't be happening... my body hasn't even regenerated, yet!' Hayai thought as he attempted to struggle.
"Are you ready, Natsu?" Kyojuro asked, while taking a Fire Breathing stance and preparing to sever Hayai's head.
"Yes!" Natsu replied as he had also taken a Fire Breathing stance next to Kyojuro.
Hayai stared at both Kyojuro and Natsu, who were prepared to end his life with their Nichirin swords. "No, no, no, no no, no!"
Before Hayai's body could regenerate, Inosuke tossed Hayai forward by the neck and both Natsu and Kyojuro quickly used a Flame Breathing to successfully decapitate Hayai's neck.
'Flame Breathing. First Form... Flame Strike!' Both Natsu and Kyojuro chanted, then withdrew their Nichirin swords in the same manner as Shinjuro once did when he was once a Flame Hashira.
Ten Seconds After Taking A Breath
"Hell yeah! We killed the demon!" Inosuke celebrated by jumping in the air.
"We did it, brother! We killed a demon and we did it, together!" Natsu gave Kyojuro a bright smile.
"Yes. You are right about that. But, our mission isn't over, yet, Natsu." Kyojuro slightly looked at the Mugen Train vessel. "We still have to investigate the Mugen Train."
"Uh?" Natsu then remembered the Mugen Train investigation. "Right." Natsu smiled and nodded. "When we go on the Mugen Train, let's take down the other demon, together! As brothers!"
"Very well!" Kyojuro raised a fist toward Natsu. "We shall defeat the demon and protect everyone on the Mugen Train, tomorrow."
Natsu's eyes sparkled as he stared at Kyojuro's fist. He knew that Kyojuro was asking for a fist bump. A big smile appeared on his face. And gave Kyojuro a bright and honest smile.
Author's Note: Next stop, the Mugen Train. I'll do my best.
Also, I noticed some of the characters were never named. So, I named some of them. The boy with the blue haori was unnamed, so I called him, Ao. Ao means "Blue" in Japanese. So I named him, due to the colored haori he wore. I know the demon is called the Slasher, but I just decide to call him, Haiya. Which means "Fast" in Japanese.