Flame Tessaiga  

After creating Kisuke Urahara's Benihime, Ailin modified Tessaiga's sheath using Crimson Shield's properties to contain a barrier.

In Inuyasha, Tessaiga's sheath also had a hidden function allowing its wielder to summon Tessaiga after releasing it.

Clang!

Facing two Captain-class Zanpakutō and seven to eight Lieutenant-class ones, Ailin felt no fear gripping Tessaiga. Rather, he felt extremely excited at finally unleashing his full power.

"Tessaiga!"

Responding to Ailin's call, the battered sheath shone with dazzling ivory radiance, expanding to over three meters long as rich Reiryoku swirled around the colossal fang.

Tessaiga's release didn't further raise Ailin's Reiatsu, slightly disappointing him.

After all, he had already released his Zanpakutō. Being able to raise his Reiatsu again by releasing another blade meant that just unsealing the Zanpakutō in his reality marble would make his Reiatsu skyrocket.

However, Ailin discovered that under his Zanpakutō's released state, unleashing other weapons and utilizing their secret technique consumed only one-tenth as much Reiryoku! What this represented was obvious.

The berserk Reiatsu was focused by Ailin into Tessaiga, miniature tornadoes swirling along the fang's blade. Then, slashing towards the seven approaching Zanpakutō Spirits, he unleashed Tessaiga's strongest technique.

"Wind Scar!"

Three heaven-rending attacks roared forth like tidal waves, drowning his foes.

"Arghhhh!"

The five Lieutenant-class were ripped apart by that devastating assault.

"Smash him, Tengumaru!" Love Aikawa's Zanpakutō spirit took the form of a three-meter tall muscular male. Facing the incoming attacks, he immediately released Shikai.

Boom!

Immense Reiatsu erupted from Tengumaru as his cleaver-like Zanpakutō transformed into a gigantic kanabō resembling a morningstar mace.

"Scorching Hammer!"

Flames coiled thickly around the spiked mace as Tengumaru swung it down towards Ailin's attacks.

Boom!

White shock waves collided with crimson flames, rocketing skywards and dyeing the surroundings red and white.

Invisible undulations blasted outwards, fluttering the spectators' robes wildly. The heavy atmosphere left everyone solemn. Things had escalated completely out of hand!

…

"Trash!"

In the skies, Kōga scowled seeing his controlled manifested Zanpakutō Spirits get crushed by Ailin after just a single clash. By now, he no longer cared about Captain-Commander Yamamoto's edict or Soul Society. 

His Zanpakutō was the strongest!

Yet this damned Ailin seemed to hard-counter him completely!

Just the fact that his countless later projected Zanpakutō were immune to his control meant that Ailin had to die! Soul Society couldn't tolerate someone with Zanpakutō he couldn't control!

"Muramasa, I want him to taste utter despair and death in the shortest time possible!"

"As you command, Kōga-sama." After respectfully bowing, Muramasa stretched his right hand towards Ailin. "Art of Shadow Bind!"

…

The collisions between Wind Scar and Tengumaru's ougi had further damaged the already ravaged buildings here.

When the dust settled, two figures with powerful Reiatsu walked out from the lingering explosions.

"Oh? As expected of captains' Zanpakutō, even Wind Scar couldn't injure them much. Then..."

Just as Ailin thought of using stronger moves, his entire body seemed bound by countless threads, unable to budge at all. After the initial shock, he soon calmed down with realization.

"This move, it's Muramasa's power!"

Although invisible, the protagonist had seen countless threads ensnaring his Zanpakutō in his inner world's reflection.

"Projection—!"

Over ten blades emerged around Ailin, transforming into a rain of swords hacking at the threads.

Clang! Clang! Clang!

With each severed thread, Ailin felt lighter. Soon, all constraints had been slashed apart and his freedom restored.

"Hmph, thanks for reminding me. If not for that move, I'd have forgotten who my real opponent was." Glancing skywards, Ailin unleashed his Reiatsu.

"Reiatsu Eruption!"

After using it to defeat Captain Marenoshin Ōmaeda, this was Ailin's second time. With Reiatsu Eruption, Ailin's Reiatsu once more neared Kōga's level.

"Flame Tessaiga!"

Roaarrr!

Responding to his call, Tessaiga transformed into a blazing fang exuding scorching flames, the nearby air rippling from the intense heat.

Ignoring the two incoming Zanpakutō Spirits, Ailin unleashed his strongest move towards Kōga.

"Flame Wind Scar!"

Three fiery shock waves tore through the air as if to drown Kōga completely.

"Damn!" 

Seeing the sky-rending attacks, Kōga's eyes flashed with fear. His ability could greatly diminish almost all Shinigami while adding their Zanpakutō to his forces. But it had no effect against Ailin's direct and overbearing assault now. Facing such might, even Kōga could only call for his Zanpakutō Spirit mentally.

"Muramasa!"

Responding to his wielder's call, Muramasa's body appeared before Kōga, ready to shield him.

Muramasa didn't oppose his master's intent at all. As long as Kōga was fine, what did it matter if he was condemned to hell?

Thus, aside from unleashing his full power against the triple flaming attacks, Muramasa also commanded Tengumaru and Engetsu to attack as well.

"Scorching Hammer!"

"Crescent Moon Rush!"