Rias and her peerage spend the next day looking for Kiba and the others. "My familiar has found Irina!" Rias said, as they headed to where she was. They found her on a trail near the forest wounded and her clothes almost rip off. "Irina, are you ok!?" Rengoku said. "I'm sorry, I failed them. I was too slow" she said. Asia started to heal them and Sona with her peerage teleported in front of them.
"What happen?" Sona asked. "She was attack by someone" Issei said. They then heard a laugh and they turn around to see Freed. "Hello devils!" he said. Rengoku took out his sword and said "Did you do this?"
"So what if I did, she was getting in my way" Freed said. Rengoku tighten his grip on his sword and said "You will pay for what you did to my friend."
"Sorry, but my boss wants to talk to you" Freed said, as the sky turn dark. A man with dark wings appear in the sky and he said "What do we have here? Two very strong devils and their peerage." He turn to Rengoku and said "And it seems we have a Demon Slayer here. Judging by that coat around you, you're the Flame Hashira."
The man chuckled and said "The last fire Hashira I met gave me a really bad wound. He was a great fighter and you look just like him." Rengoku stare at him and said "What do you want Kokabiel?"
"To get rid of the devils that live here. Starting off with that school."
Rias gasp and said "But just by doing that you'll start a war!"
"That's what I want, to start another war!" Kokabiel said, as he then vanish.
A/N: Sorry for this sum up version. I know it's bad compare to what actually happen
"He's going to make this city a battlefield, everyone in the city will die" Sona said. Rengoku then had a image of his father, Senjuro, and his friends dying from the explosion. "We can't let that happen!" Rengoku said. He started running and Rias was calling for him, but he couldn't. He wanted to get reinforcement.
Time skip brought you by this
Rias and her peerage were fighting a three headed dog. Out of nowhere, a second one appear and was about to attack them. "Fire Breathing Third Form: Blazing Universe!" someone shouted. Two of the heads were cut off by Rengoku and Xenovia. "Rengoku, you made it!" Rias shouted. "I brought reinforcement!" Rengoku shouted. The Hashiras appear and Tanjiro shouted "We're here too!"
Akeno was blasted from the sky and she started falling to the floor. "Akeno!" Issei shouted, but someone caught. "Well, I think that was a very flamboyant move from me" Tengen said, as he hold Akeno bride style. He then dropped her and said "Ok, get off of me now."
"Now that we're all here, let's go stop this man!" Rengoku said. "You're too late!" Kokabiel said, as Excalibur was already done fussing. "This city will explode in about twenty minutes." Freed showed up and grab the new sword.
Kiba approach Valper and said "I was the only survivor of the Holy Sword Project, while you kill the others."
"I remember them telling me one escape, but I never thought he would turn into a low life devil" Valper said. After a little back and forth from Valper and Kiba, revealing that they were using genetics from the kids who were in the Holy Sword project, to improve other people's chances on being able to weald Excalibur. Everyone was surprise by that, except the Hashiras who didn't knew what they were talking about.
After a little inspiration from the souls of his friends, Kiba makes a new sword that wields both devils and holy powers. "That isn't possible, those two powers shouldn't be able to work together" Valper said. Rengoku and Xenovia walked up next to Kiba, which surprise him. "Why are you guys here?" he asked them. "I want to help you destroy Excalibur" Xenovia said. "I'm here to help a friend" Rengoku said.
Xenovia summon a sword from a portal, and destroy Freed's sword really easy. Freed was getting scared, so he decided to run away while Valper was stab from a light arrow. Kokabiel laugh and said "Valper was useful for what he had to do. Now, the Red Dragon boost Rias"
"He's giving us a chance to fight him" Rias said. "Then let's take that chance" Rengoku said. Issei started using boost over and over until it was enough. "It's ready" he told Rias. Rias nodded and Issei gave her the boost. Rias felt the boost shiver all over her body and she shot out an explosion to Kokaibiel. "This is an impressive power coming from the sister of Lucifer!" Kokabiel shouted as he block the attack.
Akeno appear and she shot out some lighting. "This is impressive coming from the one who posses the power of Barkiel" Kokabiel said. "Don't tie me up with that thing!" Akeno shouted. "Barkiel?" Issei asked. "He's a general leader of the Fallen Angels who uses thunder and lighting" Xenovia explain. Kokabiel block all of the attacks and threw an attack of his own back at Akeno.
She crashed down to the ground and said "This is sad coming from Rias's peerage. We have the Red Dragon Emperor, a Holy Sword user, and the daughter of Barkeil."
"Wait, so Akeno is the daughter of a fallen angel!?" Issei said. Kokabiel then turn to Rengoku and said "And it seems your friends with the son of Shinjuro Rengoku, the Fire Hashira who gave me a hard time the last time I was here."
"Flame Hashira? Rengoku, was your dad a hashira as well?" Issei asked him. "He was, the Fire Pillars come from only the Rengoku family" Rengoku said. "If I were you, I would take this chance right now to defeat me" Kokabiel said. "Are you done talking? You're making me bore over here" Tengen said, as he walk up to the field. "Tengen! What are you doing!?" Rengoku said.
"I'm tired of this unflamboyant man trash talking you, and your friends. Issei, start boosting. We'll cover you" Tengen said, as he took out his blades. "We got you too" Giyu said, as the other Demon Slayers got on the feild. "Impressive, all the Hashiras against me with some minor Demon Slayers as well?" Kokabiel said. They all rush at him and each one took a turn on hitting him. Giyu slash at him, using his water breathing while Sanemi was on the other side using his wind breathing.
Obanai and Mitsuri threw their whip like swords around his neck and hold him down. Tanjiro and Rengoku ran up to him, lighting their swords on fire. Rengoku slash across his chest and then Tanjiro did the same thing.
Kokabiel then blasted them away but then got a hit in the face. He turn to see Gyomei holding his chain frial and axe in his hands. "This is impressive, a blind man fighting me" Kokabiel said. "What is he doing!? He could get himself kill!" Issei scream. "Don't misjudge Gyomei, theirs a reason why we call him the strongest Hashira" Rengoku said.
Gyomei started twirling his frial and he started to see Kokabiel's inner body.
A/N: Gyomei is one of my favorite Hashiras, I don't know why is he so underrated
Gyomei threw it at Kokabiel with Kokabiel blocking it with his wings. "You blind fool, that was the most idiotic move I have ever seen" he said. "Who decided that?" Gyomei said, as he was standing next to Kokabiel.
He then slash Kokabiels eyes, making him scream in pain. He then threw his frial and axe at him, making an opening for the others. "Damn you!" Kokabiel shouted, as he threw a ball of energy at Gyomei. Luckily, Xenovia cut the ball of energy in half before it could it hit the rock pillar. "Thank you, you kind soul" Gyomei said.
Kokabiel laugh and said "You guys are fighting hard for the people who have lost their masters!"
"What!?" Xenovia shouted. "Oh, I might have slip that out of my mouth" Kokabiel said. "What did you say Kokabiel!?" Xenovia shouted. "Since I am starting this war I might as well tell you, God died with the four devil kings during the three way war" Kokabiel said, shocking everyone. "How?" Xenovia said. "God.. Is dead? That's impossible!" Rias shouted.
"During that war, the devils lost all their kings and most of their high level devils, that counts for the angels and fallen angels. The pure angels couldn't increase their numbers, and purebred devils are rare."
"That... That can't be true!" Asia said. "All sides have been ruined to the point where they have to rely on humans to survive. Angels, fallen angels, devils, the leaders of the three factions had to seal away this information so that god could continue on earth."
Xenovia got on her knees and said "Lies, that's all lies."
"Why do I care anyway, all I care is that war was pointless!" Kokabiel shouted. "But then, who's been gifting us?" Asia asked. "Michael seems to be doing a good job on that" Kokabiel said. "Archangel Michael is acting as God's agent?" Xenovia said. "As long as good and evil exist, everything is fine. Why do you think the Holy Devil sword exists?"
Everyone was still shock that it was reveal that God was dead. "I let my pride get in my way" Rias said. "Enough talking!" Rengoku shouted. He raised his sword and said "It doesn't matter if God is dead, because we still have hope! And as long as we have hope, we are not backing down!"
Kokabiel chuckled and said "Hope? What type of idiot would just relies everything on hope?"
"That idiot is me. Issei now!" Rengoku shouted. Issei nodded and gave him a giant boost. Rengoku felt a little shiver through his body, and he look at Kokabiel. "Fire Breathing First form: Unknowing Fire!" he shouted, as he blasted towards Kokabiel.
Kokabiel gasp and started to throw attacks, but Rengoku just cut them down. He then went for his neck and was able to cut halfway. Kokabiel push him off before he was able to finish decapitating him and was holding onto his wound. "Damn it! You're just like your father, he almost got me with that move too!" Kokabiel said.
"Of course you almost lost to a human" a voice said, as the force field around them shatter. A light came down revealing a man in white armor. "The vanishing dragon!?" Kokabiel said surprise. "Why are you here!?" Kokabiel shouted, but then the White Dragon rip off some of his wings. "Why would a being that lower itself have wings?" the man said.
Kokabiel tried attacking him, but the White Dragon just made his attacks shrink into they disappear. "Azazel said to bring you back, and I could use as much power as I want."
The White Dragon blasted him away and was about to leave when the Red Dragon started talking him. They had their conversation before the White Dragon left. Rengoku smile and said "We did it."
"Woah, was that the move you used on Riser? That was cool!" Issei said. "Thank you" Rengoku said. "Rengoku my friend, that was a very flamboyant move you there!" Tengen said. "All I did was the same thing I did during my fight with Riser" Rengoku said. "But it was still amazing!" Mitsuri said. "It's nice to see that the Rengoku blood line can still fight fallen angels" Shinobu said.
"Ok, I just want to get something to eat now" Rengoku said.
Time Skip brought you by this
The next day, Rengoku was hanging out with Rias and her peerage. Suddenly someone came inside the club room. "Look who's here" Rias said, making Issei and Rengoku shock. "Xenovia!?" they both said surprise. "Why are you doing here?" Issei asked her. "Let me introduce you to our newest knight!" Rias said. "Does that mean-"
Xenovia showed off her devil wings and surprise Rengoku. "Sorry that you couldn't be my second knight Rengoku" Rias said. "It's fine Rias, I'm fine being human" Rengoku said. "But why did she join us?" Issei asked. "After finding out that God's dead, I realize I have no purpose. So I begged Rias to let me join her peerage" Xenovia said. "She will also be attending Kuoh academy today" Rias added.
"What!?" Rengoku and Issei said. "I hope we can work together" Xenovia said to the both them, trying to have a happy tone. "Wait, what about Irina?" Rengoku asked. "She went back to headquarters, I couldn't tell her the truth."
She then apologized to Asia about the bad things she said, and she turn to Rengoku. "I would like to fight you again some time. The man who beat both Riser Phoenix and Kokabiel."
"Technically I didn't beat Kokabiel, but I'll gladly accept!" Rengoku said. "Well, the Occult Research Club is now open again!" Rias announced.