Enmu had finally being defeated by Goku and Inosuke. After the battle, Goku, barely standing, told Inosuke his secret. Suddenly, from behind, Goku heard a voice.
"Hey, Goku-kun!" it was Rengoku.
"Kyojuro...!" said Goku, "are you hurt?"
"No," said Rengoku, "I handled those five wagons well. What about you? Any injury?"
"I'm fine," said Goku, "just a bit tired, but I'm not hurt."
"That's great!" exclaimed Rengoku, "nobody on the train died, if you care."
"Of course I care!" exclaimed Goku, "this is a great news!"
"The yellow boy and the demon girl are dragging them safe," explained Rengoku.
"Oh, that's great..." whispered Goku.
Suddenly, from the remnants of the train, the last guts of Enmu appeared.
(So... I'm dying, aren't I?) he thought, (this boy... I was supposed to kill him, not being killed by him... if what he said is true, Muzan-sama is really in danger...)
Then, Enmu definitely disappeared.
"Come on now, let's drag the passengers safe and let's head back to the headquarters," said Rengoku, calmly for once.
"Yeah, let's go..." whispered Goku. But then, Goku felt something. He instinctively grabbed his katana and sliced something.
"Goku-kun, what is it?" asked Rengoku.
"There's someone else in there..." whispered Goku. Then, Goku heard a voice.
"Excellent danger perception, demon slayer."
From the dust, a demon appeared. Pink hair, blue lines all over his body and yellow eyes. On both his pupils, he had the kanji of "Upper Three."
"Who are you?" asked Goku.
"I'm Akaza," replied the demon.
"Goku-kun, I'll handle him," said Rengoku, "you're too tired to fight,"
"Oh, just like I wanted: The Hashira fighting me," laughed Akaza. But suddenly, in Goku's eyes, something shined. Then, a flashback.
Three years ago, when his family was killed and his village destroyed, Goku saw a demon from outside the window. That demon had pink hair, blue lines all over his body and yellow eyes... just like Akaza. Then, Goku realized: The demon who killed his parents and destroyed his village was standing right before his eyes.
"No, Kyojuro," he suddenly said, "this demon is mine."
Goku stepped up, holding his Nichirin Sword with both hands.
"You'll be killed if you fight alone against him! He's an Upper Moon!" said Rengoku.
"I know, but this is my fight. Because he... is the demon who destroyed my village three years ago!" yelled Goku, pointing Akaza with his sword.
"Really? Did I do suck a thing?" asked Akaza, trying to sound casual.
"Yes, you did!" shouted Goku, "I remember perfectly how that demon looked like. You either have an identical twin, or that's really you!"
"Oh, now I remember..." said Akaza, "honestly, I didn't even know why I let you alive that day... But no problem, I'll kill you now."
"Unless... You accept to become a demon."
Goku thought: actually, he was already a demon -- a hybrid, actually -- but he couldn't say it in front of Rengoku. So, he decided to lie.
"I won't become a demon," he said, determined.
"Oh, what a pity," muttered Akaza, "well, if you don't want to become a demon then I'll kill you."
The Upper Moon rushed towards Goku.
"Stay back, Kyojuro!" screamed the boy, blocking Akaza's punch with his sword, "do not intervene! This is MY fight!"
Rengoku did so, and jumped back, observing Goku.
(He's going to be killed...) he thought, (I can't follow their movements... Is this Goku-kun's real strength? Or is Akaza holding back?)
Meanwhile, Goku was fighting Akaza, blocking his punches with the blade of his katana.
"Why don't you become a demon?" asked Akaza, "it'll be a shame to kill you! You're so powerful!"
"I already told you I won't become a demon," replied Goku, "especially if it's the demon who ruined my life who asks me!"
"Pity..." said Akaza.
In a moment of focus, Goku cut Akaza's right arm, as the demon jumped in the night sky.
"Let's see how you handle this!" exclaimed the demon in mid-air, "Destructive Death: Air Type!"
Suddenly, Goku felt hit by something.
(What did just hit me?) he wondered. Then, another air attack. But this time, Goku managed to block it with his Nichirin Sword, (it's a range attack from the distance...)
"Flame Breathing: Fourth Form -- Blooming Flame Undulation!"
Akaza's punches met with Goku's flames.
(From this distance, I can't kill him...) thought Goku, as the flames died down, (There's only one thing I can do right now...)
Then, Goku rushed forward. (Getting closer!)
The boy rushed towards Akaza and stopped inches from him. Then, with a straight slash, the boy tried to behead Akaza, but the demon jumped back and avoided the attack.
"Such reaction time... Such attack potency... It's a shame you don't want to become a demon..." muttered Akaza.
Goku didn't waste anytime and rushed to Akaza again. Now, Akaza's punches clashed with Goku's blade, exchanging powerful blows.
Then, Inosuke arrived.
"Boss!" he exclaimed.
"Stay back, Inosuke-kun! Do not get closer!" yelled Goku. Inosuke slowly nodded.
"Don't worry about those weaklings, Goku-kun! I'll kill them once I'm done with you!" exclaimed Akaza.
"You won't kill me!" exclaimed Goku, who kept exchanging blows with Akaza, "and don't call me Goku-kun! Just Goku, if you really have to!"
"Flame Breathing: Third Form -- Blazing Universe!" he exclaimed. Akaza dodged and countered with a punch, which Goku blocked.
"Catch me if you can!" exclaimed Akaza, jumping back and disappearing in the forest nearby. Goku immediately ran inside the forest.
(Where is that asshole..?) he wondered. Suddenly, Akaza reappeared in front of him.
"Nice moves!" he exclaimed. Goku tried to hit him with a down slash, but Akaza dodged. Then, the demon punched Goku. The boy spat blood and was sent flying backwards, smashing against the floor.
"Goku-kun!" shouted Rengoku.
"Are you okay, boss?!?" asked Inosuke. The dust settled, and Goku coughed up blood.
(No good...) thought Rengoku. Then, Akaza reappeared.
"Become. A. Demon."
"Like hell I will..." said Goku. The boy refused to lose.
Chapter 17 - End.