Kosaka Isshin

"Blade Thief" Kosaka Isshin is an elite operative of the Black Widow Pirates that currently acts as their Head of Operations under the alias "Izanami" (イザナミ). He is a founding member of the crew and one of their most vital subordinates, for he is in charge of the vast empire's finances and is a proxy for Daddy L. Legs when the situation requires it.

He allegedly possesses a former identity by the name of Charmers Dion, who was once a in the, but the details behind this aspect of the man are concealed. Though, it appears as if this identity is connected to former Admirals Alfred Glave and Warren D. Ralph.

Daddy L. Legs
During her time as Fukuoka Koyuki, the Black Widow had loved Isshin with all of her heart. The kindness he exhibited in such a perilous situation was one that she had never received before, especially considering the discrimination against her powers. While he did not reciprocate this affection due to ignorance, Isshin valued the life of Koyuki as a precious comrade. When Koyuki was targeted by a Vice Admiral, Isshin had dared to sacrifice his frail life without hesitation to protect Koyuki, believing that her strength would guide their country to a new era.

As it stands, the relationship between the two does not appear to be romantically inclined. Whether that was due to Legs becoming engrossed in her responsibility as a Pirate Captain, or other reasons, is left undisclosed. However, Isshin does not seem to forgive depiction of his Captain in a negative light.

Aoshin
Although the two were acquainted during their time in prison, they did not bear a strong relationship in the slightest. In the present day, Isshin and Aoshin are seemingly on equal terms. Despite Aoshin finding Isshin's serious attitude somewhat cumbersome, he doesn't appear to pay it any mind. Likewise, Isshin finds Aoshin's perverted attitudes somewhat grating, but he is fully aware of the First Division Commander's strength within the Crew.

Abilities and Powers
Being the Secretary of Finance for the Black Widow Pirates, Kosaka Isshin is one of the most influential men in the world. His decisions shape the growth and stability of the empire belonging to the Yonko Daddy L. Legs, which includes her magnanimous territories and armies. Without his guidance, the citizens and soldiers of the Black Widow would be ruined, and few would know of opportune areas to conquer territory. It is for this very reason that Isshin has been dubbed "Izanami" (イザナミ), for he created the structure of the world that "Izanagi" must now protect.

Although not possessing a strict combat role among the Black Widow Pirates, he is nonetheless one of the Yonko's closest subordinates, and possesses power befitting of one. He has established himself a fearsome reputation across the New World and beyond as the "Blade Thief" (剣盗), as a man who steals both technique and lives with his blade. His presence forces inferior combatants to cower, every action he takes is a demonstration of his strength, and every battle he takes part in leads to victory. To this end, he has served as a proxy for his Captain on several occasions.

Isshin himself bore enough skill to fight on-par with an Admiral to the point where he forced him to retreat, lest he incur the wrath of the Black Widow Pirates. Notably, during this confrontation, Isshin was not making use of his full strength. Even the likes of Alessandra acknowledged Isshin's strength, but noted his aura as "steadfast" and not prone to violence.

Physical Prowess
Isshin is an extremely powerful physical combatant, with enough strength to go head-to-head with the likes of Warren D. Ralph in multiple physical clashes without being forced on the defensive, all the while the environment around them had been rendered asunder due to their individual strengths. In fact, their initial clash between sword and fist caused the entirety of Tariland Island's small town to be awakened by a thunderous roar, despite both combatants holding back. Said roar was accompanied with a strong shockwave that reached the island's outskirts. He is capable of imbuing his strikes with enough strength that the air pressure that releases from a half-hearted swing can cause the ground to shift in response, creating a makeshift barrier from the soil. His strength was enough to even disrupt an attack from the Admiral itself by pushing his sword against the man's shin, which had been raised to perform a powerful.

Isshin's raw speed, agility and dexterity is enough to make use of afterimages with strict ease. Likewise, he was capable of effortlessly keeping on-pace with the Gold Fist, despite the Admiral's attacks all being blitz-like. The momentum he drew from his speed continuously empowered his attack and defense, balancing any differences in strength. His balance and self-control is also notable, for despite various changes in terrain, his stances and attacks were not compromised in the slightest.

Isshin also bears considerable endurance and durability. Despite repeated physical clashes and onslaughts of attacks from Ralph, he continued to fight at such a high scale without once showing signs of exhaustion. However, following the battle and extensive use of his Devil Fruit powers, he did seem drained.

Past
Isshin was remarked to be a prized from the. However, a silent protest against the actions of the corrupt Daimyo lead him to be imprisoned by a by the name of Charmers Dion.

While in prison, Daddy L. Legs, who went under the name Fukuoka Koyuki, would find herself in love with him due to his benevolent demeanor despite his perilous situation. He would share his food with her and find comfort in knowing that at least one of them would survive this ordeal. For undisclosed reasons outside of his protest, he was placed on death's row, and thus gave even more of his food to the woman as another act of protest.

When the prison break was organized between Aoshin and Koyuki, Isshin was one of the major players that contributed to their fighting force. Despite his sickly nature, his abilities enabled him to fight back against any number of onslaughts without any fear. However, when Koyuki had been targeted by a Vice Admiral with a lethal technique, Isshin knew there was only one option available to him. Rushing in with all his strength, he diverted the rocket-like attack aimed at Koyuki and, with his, directed that very energy to the ground. The subsequent explosion and the effort he exerted in travelling at great speeds broke his frail body, until he was motionless and believed to be dead.

As Koyuki and Aoshin escaped the island on a Marine's vessel with Isshin's body, they found that his heart was still beating and that there was a possibility for him to live. Koyuki immediately performed first-aid while a on board the Marine vessel was quickly forced into cooperation, stabilizing Isshin's condition and allowing him to live. After several years, he would grow in infamy as the Fifth Division Commander for the Black Widow Pirates.

Quotes

 * (To Warren D. Ralph) "We are not like the other Yonko. The Black Widow Pirates are an empire composed of the finest warriors. I am here, much like you all, to represent the Black Widow Pirates and pay our respects to Sir Glave. Regardless of the differences in our ideals, he was a warrior worthy of respect. But I am also here on behalf of the Black Widow to give you all a warning. If you dare to interrupt our activities in the fragile state you are in, we will not hesitate to engage in war with the entire World Government. So think carefully as you approach me, Admiral Ralph. I am fully willing to fire the beacon of war."