Scyther Sonic!!

Akehende's skin was replace by a distinct glossy black fur, his eyes now resemble cat eyes with yellow pupils and his once smooth fingers are now sharp claws. He transformed into a panther, a black panther.

[Cat-Cat Fruit, Model: Black Panther]

He was in his full beast form.

"A panther?!" Killer exclaimed in surprise, he never thought that his enemy still had an ace up his sleeve "So you're a devil fruit user, and a Zoan on top of that. No wonder you have great physical strength and speed" 

"GROWL!!" Without wasting any time and while in his full panther form, Akehende lunged at Killer aiming to slash his chest with his sharp animal claws. 

Clang! Clang! Killer utilized his Punishers to block the attack before he responded with swift kick aimed at the panther's face. However, the Rear Admiral's animal form granted him more speed and agility than he already possessed, which allowed him to evade the attack with ease.

He then rushed at Killer once more, his mouth wide open and revealing sets of sharp fangs and teeth aimed to bite the masked pirate's neck. 

Killer predicted Akehende's move and skillfully evade it by leaping backwards, but the latter didn't end his attack right there and he proceeded to close the distance once more, taking the former by surprise and slashing his chest with his claws.

SPLASH! Killer held his chest in pain, but there was no time for complaining. His eyes were locked at his opponent before rushed towards him and then leaped in the air, raising his blades upwards and then striking down with enough strength to unleash two powerful flying slashes that flew to Akenhende's direction.

Killer didn't stop there as he didn't want to give the Rear Admiral any time to think about his next movements, so he immediately closed the distance from behind and swung his blades, striking down his enemy and inflicting a large cut on his back while sending him crashing into a wall.

Akehende screamed and howled in pain after receiving the attack, but he quickly got up. He growled in anger before his body started slowly transforming once again.

This time he went from being a full black panther, into a humanoid version of it. He still kept the animal's characteristics, from the black fur to the cat like eyes and sharp claws and teeth.

He also picked up his massive two-handed sword again from the ground, this time he planned on using it.

"Haaa…I didn't expect you to be this strong, you're a though one I'll give you that" Akehende commended Killer's strength. Right now, he was in his hybrid form, which along with his full beast form such as every Zoan fruit enhances his physical power even more by granting him things such as enhanced strength, durability, speed and agility, powerful teeth and jaw, sharp claws, enhanced senses, and enhanced climbing and jumping capabilities.

And since he relies on his physical power often to use martial arts like the Rokushiki, the fruit is more dangerous and advantageous in his possession. 

Killer flexed his Punishers after he witnessed that, cautious and ready to take on any attacks "Huff…Huff…I don't need to hear that from you" he said while he was breathing heavily, the injuries he suffered from this fight were starting to affect him, he lost a lot of blood and fight consumed a lot of his stamina. 

He knew that he would reach his limits soon if he doesn't defeat his enemy. Akehende wasn't completely fine either, although Killer didn't land a lot of attacks but the ones that managed to hit him dealt a lot of damage.

"I wonder how much longer you can hold" Akehende's smirked in confidence while gazing at his opponent "Razor!!" He muttered, leaping in the air and then using a combination of Geppo and Soru, where he used Soru in a zigzag motion midair, allowing him to use extremely fast movements in three dimensions. 

Killer was having a hard time following Akehende's fast movements, so he got into a defensive stance and waited for his opponent to make strike first.

SWOOOSH!! Akehende disappeared and reappeared several times in a zigzag motion mid-air before he propelled himself towards Killer with his sword swinging diagonally, aiming to cut him using his high speed.

BAAAM!! Killer struck back. Their blades connected in an instant, generating a powerful shockwave.

Akehende wasn't finished yet, he spun around quickly in a circle while standing on one hand, and then performed Rankyaku with both legs to create a circle shaped Rankyaku which radiated outward. 

"Rankyaku…Wind Swirl!!" The attack was powerful enough to cut through some ships nearby while sending Killer rolling on the ground.

"I need more…more power and speed to match him" Killer muttered as he lifted himself up, his body was shaking, covered in sweat and blood. He spun the sickles on his Punishers with more speed than before, and then he dashed towards Akehende and slashed him in the chest.

Akehendi held his ground and hardened his muscles to the level of iron "Tekkai!"

ZWOOOSH! CLANG! This time unlike before, Killer's slash did affect Akehendi even though he used Tekkai.

Akehendi groaned in pain while holding his bleeding chest "You little shit, I'll show what real power is!" He declared, jumping in the air and creating a large Rankyaku in the shape of an eagle, but instead of using his legs, he used his claws in his half panther form.

"Rankyaku…Victory Eagle!!" This Rankyaku has a much wider range, greater attack power, and is capable of cleaving even steel.

The attack prompted Killer to swiftly jump out of its way. The Rankyaku then proceeded to cleave a building behind him in half.

"That was dangerous!" He said as he barely dodged in time.

The fight between the two figures continued for a few more minutes, each time Killer rushed to his enemy he tried to increase the power of his attacks and the speed in which the sickles on his Punishers spun ,until he was able to damage Akehende even while using Tekkai plus the enhanced durability given by his Zoan fruit. 

And although Killer couldn't match his speed often, he was able to read his movements and predict his attacks instead.

Now the fight between the two was reaching its peak as both figures suffered from serious injuries and signs of fatigue were evident on both.

"Huff…Huff…Two-Handed Sword Style…Heaven Cleaving Slash!!" With a mighty swing from his sword Akehende unleashed a powerful flying slash towards Killer followed by several Rankyaku. 

Clang! Clang! BAAAAM! Killer skillfully dodged some of them while redirecting other ones away before he dashed towards his opponent, closing the distance and forcing him to engage in close combat. 

Both fighters were very skilled in closed combat as they clashed blades evenly. Asuka Town's once Port that used to harbor ships and the buildings near it that were buzzling with people, is now just shipwreck and rubbles.

The people living in town were all fearfully watching the two figures from a safe distance, hoping for the fight to end sooner before more destruction befall their town. 

"Are they even humans?"

"Damn pirates! I've lost my fishing boat because of them. How am I supposed to earn a living now?!" 

"Let's hope this ends sooner before they cause any more destruction to our town"

Kureha was still observing Killer's battle.

"Looks like we're gonna have a winner soon" She remarked. 

Killer and Akehendi were both pushed back after their clash. The latter made a stomping motion, blasting the air straight ahead in a line towards Killer like a bullet.

"Rankyaku…Bullet!"

Killer quickly sidestepped before responding with an attack of his own. He wildly spun around himself with his weapons strong enough and with enough speed to create a small tornado of small and sharp wind blades that flew to Akehende at high speed, inflicting several cuts on his body. 

"Dicing Winds!!"

"Unh!…such a strength!...Soru!!" The latter didn't care about his injuries and after dispersing the tornado with swing from his sword he closed the distance between him and Killer, aiming to slash his neck. The latter moved his body avoiding a fatal attack, but he was still slashed in the left shoulder. 

"Huff…You're getting sloppy" Killer mocked while glaring at the Rear Admiral.

"Then I shall use the strongest sword attack of all to cut you in half!! Time to end this fight, Killer!!" Akehende declared with a serious face, he breathed deeply before he clenched his sword with two hands above his head, ready to perform a vertical attack from a distance.

"Phew…You'd better drop-down on your knees begging for your life before it's too late"

"Hmph…You're the one who's gonna beg for his life in a second, fool…Huff…Huff…" Killer responded before he raised his arms and prepared for his attack as well. 

"Very well, have it your way then…"

Killer stood calmly in his place before he started spinning the sickles on his Punishers at a high speed. 

ZWOOOOOSH!!

'Not enough speed…more!' Killer exclaimed in his head while increasing its speed.

Akehende hardened his arm muscles before delivering his attack "Two-Handed Sword Style…Earth Shattering Slash!!" With a fast and mighty downward swing, he sent an incredibly fast and powerful sword slash that shattered the entire ground in front of him while flying at Killer's direction.

ZWOOOOOSH!! 

'MORE!!' Killer kept increasing the speed of the sickles until they reached the speed of sound creating the illusion that the sickles increased in size dozens of times. With a simple swing he blocked the slash and sent it upwards.

"He stopped it?!!" In Akehende's shock Killer rushed towards him "He's blades increased in size!!" 

The moment Killer closed the distance, he swung his Punishers at Akehende prompting the latter to use Tekkai and his sword to protect himself.

But it was useless, as the blades spun at the speed of sound, they created a soundwave slash that bypassed external defenses and damaged his opponent from the inside.

"Scyther…Sonic!!"

SPLASH!! Akehende's eyes rolled back while throwing a mouthful of blood as the attack caused immense damage to his insides, rendering him unconscious at the spot.

"How do you like that? Mister Rear Admiral!"

"Not bad kid" Kureha smiled after witnessing Killer's victory. 

"Let's see…" Killer stood in his above his defeated opponent's body. Even though he achieved victory, he was already at his limit, this was his final attack and if didn't work it would have meant his defeat. 

"…You have a pretty interesting devil fruit, we have a few members in the crew that could put it in a good use"