"All Things in the Universe, Turn to Ashes. Ryujin Jakka." Yamamoto says, activating his Zanpakuto's Shikai. (first awakening/form)

His sword is clad in fire as the temperature in the surroundings significantly increases and I'm assaulted by an intensely hot and powerful Spiritual Pressure.

"Chase the Moon. Hati." As I activate my own Shikai, my Greatsword turns into a dark blue and golden Glaive.

The Sun suddenly disappears from the sky as it turns dark and the Moon takes its place in the sky. This phenomena is noticed throughout Soul Society, causing widespread fear and chaos.

I can see everything that is touched by moonlight. I feel my influence over water everywhere, but especially focused on the oceans.

Suddenly Captain-Commander Yamamoto disappears using Shunpo and reappears beside me as he slices his sword through empty space.

Without hesitation, I spin around, burying my heel in his chest, launching him back.

Yamamoto, back where he started, stares at me with just the slightest hint of confusion as to what just happened.

"Many animal species rely on the moon to navigate. Using and manipulating that same concept, Hati here can disorient my enemies." I say, holding up my Glaive.

Yamamoto looks at my Glaive for a second and then looks at the Moon hanging in the sky, even though it's noon.

"Moon based powers? I'm not impressed." Yamamoto says before he drops his Captain's Haori and the upper half of his Shihakusho, revealing his muscular physique.

"Jokaku Enjo" (Fortress Blaze) Upon uttering the phrase, an enormous stream of fire launches from Yamamoto's sword and surrounds me, trapping me in a sphere of fire.

For about five seconds the temperature of the flames constantly increases until they reach the temperature of the Sun's surface.

After a few more seconds the flames die down, revealing me, completely unfazed and unharmed.

"Hmm... maybe a little impressed." Yamamoto says before he holds his blade upside down and plunges it into the ground. "Ennetsu Jigoku" (Flames of Hell)

Seven lines of fire spread from Yamamoto's blade, along the ground, reaching towards me.

Seven enormous pillars of fire burst from the ground, surrounding me.

"You've already tried burning me. It doesn't work." I say before I raise my Glaive over my head. I channel a large amount of reiatsu through the Glaive as it creates a layer of water covering the blade.

"Hydro Claw." I say as I swipe the Glaive downwards in Yamamoto's direction, creating four blades of highly compressed water, cutting through everything in their path, including one of the flame pillars.

As the blades reach Yamamoto, he Shunpo's out of the way, just in time to avoid three of them. The last one cuts him across his left shoulder, down to his elbow.

"Time to punish this youngster. Bankai: Zanka no Tachi." (Blade of Ember) Upon activation of his Bankai (second awakening), the temperature increases even further, causing the water in the atmosphere to evaporate.

Yamamoto's Zanpakuto, Ryujin Jakka, transforms into an old, scorched katana. Instead of being engulfed in flames, it absorbes all the flames it produced during the fight so far, trapping the heat inside. This raises the blade's temperature to 15 million degrees Celsius, the temperature of the Sun's core.

Yamamoto's body itself is now also covered in an armor of heat, reaching the same temperature as his blade.

The combination of both these abilities ensure that anything Yamamoto attacks is completely eradicated from existence. And anything or anyone that tries to touch him meets the same fate.

"Zanka no Tachi, Minami." (Blade of Ember, South.) After saying the name of the ability, Yamamoto plunges his blade into the ground again. This time producing a different effect.

A large crevice opens up in the ground between us as scorched corpses rise from it. Every one of them, someone who fell to Yamamoto's flames in the past.

"Crescent Moon Blast." I swipe my Glaive horizontally, producing a blast of pure blue, ice-cold Reiatsu in the shape of a crescent moon.

The further it travels, the bigger it becomes. When it reaches Yamamoto's ash zombies, it cuts all of them in half and freezes them solid.

As it's about to reach Yamamoto himself, it burns into nothingness as if it reached an invisible barrier.

"Impressive abilities. Maybe I should fight fire with fire. Chase the Sun, Sköll!" As I activate Sköll's Shikai, the Glaive in my hand turns white.

The sky immediately lights up as the Moon is replaced by the Sun.

"No Zanpakuto can manipulate more than one element." Yamamoto says in an accusatory tone.

"Who decided that? I will decide what my Zanpakuto can and cannot do. Your only job is to be cut down by it." I say, before I shunpo in front of Yamamoto and swipe my blade towards his neck.

*CLANG!*

Yamamoto blocks my Glaive, but my overpowering strength pushes his blade back and embeds Sköll in his shoulder, just below the neck. Immediately Sköll starts to greedily absorb the heat coming off his body.

I raise my leg and kick Yamamoto in the chest with a Spartan kick, launching him back and into the ground.

Yamamoto stands up, breathing heavily as he assesses his wounds. He then looks confused at what just happened for a second, before I explain.

"In Norse myth, Sköll was cursed by Odin to chase the Sun forever, until she would one day devour it. A creature that can devour a Sun, cannot be burnt by it. Your flames only strengthen her."

"Hahaha!" Yamamoto starts laughing almost maniacally. "I lose. Stronger, faster, powerful Kido and my flames can't burn you? There's nothing I can do to you. If you were a Shinigami, I would've made you the new Captain-Commander of the Gotei 13 right now."

Yamamoto seals his Bankai and his Zanpakuto reverts back to a generic katana before it's sealed in his wooden cane again.

I then seal my Shikai and my Zanpakuto reverts back to a beautiful single-handed greatsword.

"Why are you here? You haven't killed anyone other than Aizen and you showed us why you did that. Clearly you don't actually mean to antagonize us, so what do you want?" Yamamoto asks.

"I wanted to learn the ways of the Shinigami. And I have. Allow me to grant you a parting gift to thank you for all I've been taught." I say before I Shunpo in front of Yamamoto and grab his arm.

I exchange his knowledge of all the Shinigami techniques for my knowledge of the future of this world.

I show him what would come after Aizen's fall if I hadn't just killed him. The Fullbringers, who wish to rob the Shinigami of their powers. The Zanpakuto rebellion, led by the Zanpakuto Spirit Muramasa. And last, but most dangerous, Yhwach and his Wandenreich and Sternritter Quincy's.

"Prepare as best you can. I advise you to help the boy, Ichigo Kurosaki, to achieve his full potential. Goodbye Yamamoto, and good luck." I say before I snap my fingers and all the buildings that were destroyed in the fight just start to reassemble and all the damage is repaired.

I then teleport into my own realm, where I have a portal machine that is linked to the compound back in Danmachi.

I make my way through my realm as I'm greeted politely by the people who still live in the warships we brought from the Doom world for now.

I make my way to the portal and step through.

Immediately I hear wings fluttering as Alice comes flying towards me as a swarm of bats. The bats all fuse together, forming my wife, who looks... angry?

'Oh shit. I didn't create a portal with my claws so I didn't go back to the moment I left.'

"So, how long was I...?" I start, a little nervously.

"Two days! Without so much as a whisper of where you went or how long you'd be gone." Alice says, unamused.

"Okay, I see. That's pretty bad. But... it wasn't entirely my choice. I had to put my mind right."

"You finally fixed your anger issues?" Alice asks, now suddenly cheerful.

"Yes, but I also know how my mind was corrupted. I have permanently fixed the symptoms, now I still have to fix the underlying cause."

"And when you've done that we can travel together like we planned, right?" Alice asks, smiling brightly at the prospect.

"Exactly."

"Then what are you standing here for? Go! Fix it." Alice says, while shooing me back through the portal.

"I've had a long day of fighting dangerous foes with my life on the line. I thought I might spend some time with my wife and children."

"Life on the line...? Please. You probably said Boo! and they all fell on their asses." Alice says, jokingly.

"Haha, that's a more apt description than you might think, actually.

Alright, I'll go. I'll be back soon." I say before I step back through the portal and raise my claws in the air.

"Alright Rob, send me wherever you think I should go." I say, before I swipe my claws through the air, creating another portal.

Just like previous times, I'm launched through the void between the Multiverses, where every star in sight represents a different Multiverse.

I quickly reach one where I can feel a significantly vast amount of magic, despite the fact I'm not even there yet.

A portal opens before me and I step through.

"Gryffindor!"

Right in front of me, an eleven year old, bespectacled boy is sitting on a chair, wearing an old, pointy hat as he stares at me, fearfully.

My sudden appearance from a portal causes quite a ruckus among the rows of children sitting behind me. As well as the teachers sitting behind the boy, some of whom have their wands pointed at me.

I'm in the Wizarding World. Right in the middle of the sorting ceremony. And judging by the boy who's sitting before me, getting sorted into Gryffindor, I'm here in Harry Potter's first year.