(After the incident that resulted at the extinction of Onis due to the deaths of Styx and Acheron, Kirihito contacted someone.)

Kirihito: Hello? Yes, yes, Kirihito here. I want to ask you a favor. Could you please carve two stone stele to form some tombs? Yes? Good. Go to the Oni Village, and crave the following names.

(Kirihito speaks their names, but not their real names as he promised to keep said names a secret. After he finishes the contact he walks past his wife.)

Kirihito: Take care of our little girl. I'll be back.

(He keeps walking as he has something on his mind.)

Kirihito: (in mind) Poor Styx and Acheron... to think their existence would be short-lived because of this damn war.

(As he walks past a room, we see Caelus Rose having a talk with Zen Maverick as they are watching over the unconscious Samuel, Rumble and Frenzy.)

Zen: (turns to Caelus) What happened to him?

Caelus: Phase 6 Protocol: Execution of organic life forms. I tried to lock it, but Dreadwing found me... before this day... only Starscream was a prey for Soundblaster... (eyes widen) Oh, shit... I shouldn't remember that...

Raymond: Wait, Phase 6? What about the other five?

Caelus: First- invasion, Second- Collecting information and introducing human clones into society, Third- Active participation in the enslavement of the planet. The fourth is the beginning of the cyberforming of the earth. The fifth is the elimination of resistance...

Riku: And the last one...

Caelus: The sixth phase is very rare... if the population of the planet is too strong, then Sixphasers are called. There are only four of them and each one is dangerous... Overlord is an unkillable warrior. Sixshot- retired, but still dangerous. Sky Shadow is a mercenary, but very secretive. Of all of them, only  Overlord is dangerous. It is not taken by nuclear missiles, nor the explosion of galaxies... nothing.

Zen: We'll find a way to deal with him.

(Opening Theme)

https://youtu.be/6hpaKcnplAA

(After the opening, Kirihito is seen arriving at the Oni Village as he sees Kagerou holding both Dragon's Shinigami and Naught.)

Kirihito: You came too, I see.

Kagerou: They deserved a neat funeral. They fought to their last breaths for a noble cause after all.

(Kagerou then places Dragon's Shinigami on Styx's grave, and then he places Naught on Acheron's grave.)

Kirihito/Kagerou: (unison) Our condolences, comrades. We had a little time together... but they were good times.

(Kagerou then brings a bottle of wine and two glasses as he fills them. Kirihito picks one of them.)

Kagerou: They had resilient and indomitable will.

Kirihito: And chose death to protect their honor and that they would rather die and be reunited with their kin in glory than live in the night and hear gossip about the Oni.

Kagerou/Kirihito: (unison) To Styx and Acheron.

(They toast and drink their wines, Kagerou starts doubting his own ideals.)

Kagerou: Am I really trying my best?

Kirihito: Huh?

Kagerou: Am I really fighting to accomplish my ideals?

Kirihito: What do you mean?

Kagerou: I mean... The Dragons want to destroy the Oni, the Oni want to destroy the Dragons, humans fight each other. (holds his head) These events are making me so confused...

(Kirihito then pats Kagerou's shoulder.)

Kirihito: Just follow your beliefs. Keep fighting for what you believe in.

(Hearing Kirihito's words, Kagerou recovered his determination.)

Kagerou: Thanks, I'll protect everyone around me so that the world will be peaceful.

????: So you decided to mourn for such worthless scums, didn't you?

???? 2: If they just died forgotten like the trash they are...

(The two turn to see Rias, Asia, Rossweisse, Issei and Vali (who somehow survived the attack of Soundwave) as they prepare to transform.)

Kivat 2nd: Time for your extinction has come, devils.

GABURI!

SKULL!

Kagerou/Kirihito: Henshin!

SKULL!

(They transform into their Kamen Rider Forms, and point at the devils.)

Skull/Dark Kiva: (unison) Now, count up your sins.

Rias: You'll be the ones counting up your sins, weaklings!

ValI: I'll finish you off, and then destroy what you built for those two worthless scums!

(As they start fighting an aurora curtain appears, and Kamen Rider Millennium comes in along with his team as Issei recognizes him.)

Issei: (stern) You...

(Issei charges at Millennium, but Sasword prepares to counter.)

Sasword: Clock Up!

CLOCK UP!

(Sasword then dashes at Issei and kicks his stomach, multiple times before time flows back to normal.)

CLOCK OVER!

(Issei is sent sprawling as he gets up and coughs blood.)

Issei: Ugh... how dare you?

(Then Chris Belmont comes in with the girls from Riser's Peerage, Kuroka and Le Fay, much to their surprise.)

Rias: Riser's fiancees... Koneko's sister...

Vali: (stern) What's the meaning of this?

Chris: They're mine now, weak devil. And they'll help me to exact my revenge on this world!

(Then the riot breaks out. Millennium throws a flying kick at Rias. Sasword and Kuroka pound away at each other. Saga blocks a high kick from Ravel. Knockout transforms into his Alt Mode as Rossweisse dives in with her fist. Zero-One and Karlamine draw their blades. Orga summons his sword while Le Fay readies an attack. Ohma Zi-O grabs Bulent by the throat. Marion tries to fight off Eula, who has her in a bodyscissors. Yangyang leaps back from a slide from Chris. As Issei manages to get up, Ddraig speaks up.)

Ddraig: This is the Oni Village.

Issei: I know... (to Vali) Hey. (Vali turns to him) Let's destroy this place!

Vali: (nods) Got it. It's a collateral damage anyway!

(They then turn to the graves of Styx and Acheron.)

Issei/Vali: DRAGON SHOT!

(They fire a blast on their graves, creating an explosion.)

Kirihito/Kagerou: (eyes widen) NO!

Rias: (smirks) YES!

(As the dust settles, something surprised them. Ikki and Stella are seen wielding Dragon's Shinigami and Naught.)

Issei/Vali: What?

Millennium: How is this possible?

Raymond: I don't know either.

Ruan Mei: (comes in) I do.

(Everyone turns to Ruan Mei, who remembers what her mother said.)

(Flashback)

(A young Ruan Mei is seen training swordsmanship with her mother as the latter says something.)

Ruan Mei's Mother: The weapon created always retains the consciousness of the person who forged it.

(Flashback Ends)

(Ruan Mei realizes that Styx and Acheron had left their last thoughts in the two swords. The Dragon Warriors get shocked as well.)

Yuuji: These swords...?

Il Sindaco: ...Can be used...?

Damian: ...By other clans?

(Kagerou then remembers something as well.)

Kagerou: For swordsmen, after they die with their wishes still unfulfilled, their last bit of thought will be left inside their weapons. And if anyone is eligible to inherit their will, the previous owner's consciousness will let the successor use their full power but only for a short time.

(Ikki and Stella then prepare to fight Issei and Vali.)

Ikki: Get ready to lose, pervert!

Issei: GRAAAAH! I WILL NOT BE DEFEATED BY A MERE LOW-CLASS SWORDSMAN LIKE YOU!

Vali: I'LL MAKE YOUR GIRL SUBMIT!

Stella: (scoffs) Like I'm gonna lose to a disgrace like you.

(Issei tries to blast Ikki, who dodges the attacks while recreating all of Styx's skills until he finally unleashes the most powerful technique Styx had ever performed.)

Ikki: Jū Ni no kata: Uoza no dai saigai!

(Ikki ceases all body movements and enters a state of complete tranquility, deflecting, blocking and cutting any incoming attacks from Issei with imperceptible speed with his blade. Then he appears behind Issei, having already moved and unleashed a delayed-barrage of sharp water sword slashes that completely lacerated him before summoning multiple towering tidal waves and causing them to slam downwards on Issei with tremendous force. Leaves the sign of Pisces on the ground.)

(As for Stella, her left arm goes red while her hair goes white, and then everything goes grey as she slashes Vali six times.)

Stella: Slashed Dream Cries in Red!

(Then both Ddraig and Albion are separated from issei and Vali.)

Issei: (shocked) No.

Vali: ALBION!

(Damian is about to make a move, but then the gates of hell opened, revealing Styx and Acheron along with the other Oni members dragging both dragons to hell, Dragon's Shinigami and Naught followed suit and flew to hell.)

Issei/Vali: NOOOOO!

Chris: (smirks) This is my chance!

(Chris and his "harem" are about to attack, but then many soul chains bind him, Issei and Vali. All three of them are tied up on a boat made of bones.)

Issei: WHAT NOW?

(Then a familiar whistle is heard as a cloaked figure comes in. Chris sees a familiar nose.)

Chris: A werewolf?

Vali: (scared) No... I don't think it's a werewolf... It's...

(The figure removes its hood as it eyes glow red as it smirks like a psychopath.)

Death: DEATH!

(The trio gets scared shitless as Death then speaks in a normal tone.)

Death: And I don't mean it metaphorically, rethorically, poethically, theorically, or any fancy way. (smirks) I am Death, the judge of Hell, one of the subordinates of Izanami, the queen of hell. STRAIGHT. UP! And I'm here for you, Chris Belmont, Issei Hyoudou and Vali Lucifer.

Chris: But, I am immortal!

Issei/Vali: And we're still alive!

Death: (chuckles) You know, I'm not a big fan of harem, NTR, or any other bullcrap. I think the idea of "one husband, many wives" a nonsense. And neither of you valued any of them. So, how about we end this now?

(Suddenly Riser turns to Death, and screams in anger)

Riser: THIS IS CHEATING!

(Death then throws his one of his blades at Riser, and it hits his forehead, making him faint.)

Death: Shhh, don't tell.

(Kagerou realizes something about Death.)

Kagerou: Of course, according to the Japanese Belief, Izanagi is the ruler of hell.

(At that moment, Tiamat also appears.)

Death: Go on, Tiamat. Speak the truth about the massacre of the Onis.

Tiamat: (sighs) It was us dragons who drew the first blood and waged war, because we wanted to enslave the Oni. What Styx and Acheron did was just legitimate self-defense.

(This leads the Dragon Warriors to lower their heads because they found out they were in the wrong side.)

Death: other Oni had chosen not to reincarnate and become residents of the underworld. Acheron became the guardian of the River of Death and Styx became the guardian of the Bridge of Reincarnation to atone for their mistakes. Although Izanagi gave them the opportunity to return to earth because they were the ones who wanted to protect what was left of the Oni, they refused because there was nothing left for them to be attached to on earth.

(Rias get angry at Death.)

Rias: RELEASE MY BELOVED ISSEI RIGHT NOW!

(Death chuckles deviously.)

Death: I can't. I'm just carrying my duty to bring them, or like Lord Izanagi likes to say... call those three sinners down for judgment. 

(Finishing his sentence, Death returns to the boat and rows it to the underworld with three sinners tied in the boat. Rias sheds her tears, and then she turns angrily to the heroes.)

Rias: IT DOESN'T STAY LIKE THAT!

(She then teleports herself, Asia and Rossweisse back to Union Academy.)

(The heroes look at the graves of Styx and Acheron and see white spider lilies on their graves.)

Millennium: What's this?

Stella: (turns to Millennium) These are the white spider lilies, they represent purity. Although they killed many Dragons, it was because they wanted to protect what was left of the Oni. They would rather die to protect their purity and honor than live in humiliation and be controlled like puppets.

(Ruan Mei looks at Damian, and glares at him.)

Ruan Mei: I know... (points at Damian) Because HE had intended to turn Acheron into his Demon Moon and force Styx and Acheron to fight each other.

(Both Dragon Warriors and Cybetronians now understood their intentions and felt they owed Styx and Acheron a sincere apology. Samuel comes in along with Rumble and Frenzy.)

Samuel: To think... we were... misjudging... them...

(Kirihito remembers something.)

Kirihito: If Oni had the ability to continuously recover, then why did they disappear in the previous battle?

Kagerou: The technique of releasing all the power in the Oni Bloodline will help the Oni achieve absolute power, but in exchange, the regeneration ability and immortality will not work and the Oni will be vulnerable. hurt more than ever. So the technique of releasing power at that time was the last trump card in an emergency.

(They then leave the deserted Oni Village.)

(Meanwhile in the Underworld, Death is seen with Izanagi, Acheron and Styx, with Izanagi being the presiding officer, and both Onis as executioners.)

Izanagi: Chris Belmont, Issei Hyoudou and Vali Lucifer. You shall be punished with eternal torture and not allowed to reincarnate. Chris and Issei's punishment will be at level 2: Lust, and Vali's punishment will be at Level 7: VIolence.

(As the screen goes black, the screams of agony can be heard from Issei, Vali, and Chris.)

(To be continued.)