Samehada

is a large sentient sword, comparable in size to the Kubikiribōchō. It is described as "the most terrifying of all the Seven Swordsmen's blades" and even earned the title of, further adding to its fearsome reputation.

History
After Kisame Hoshigaki killed Fuguki Suikazan the previous owner, the blade came into his possession. The two had a long history together and during this period, confronted various renowned shinobi on several occasions, with their pairing leading Kisame to become regarded as a. They were together for so long in fact, that their chakra signatures eventually became identical, which Kisame could use to his advantage by concealing himself within Samehada in order to avoid detection by sensors.

During Kisame's initial fight with Killer B, Samehada grew fond of the taste of B's particular chakra and ultimately betrayed Kisame, returning some of the chakra it had previously absorbed from B during their battle and even shielding him from Kisame's attacks. Despite this, Kisame was still able to force Samehada to comply to his commands, allowing him to hide within it and infiltrate Kumogakure as a spy, before forcefully using it to absorb B's chakra when his presence was exposed.

After Kisame's death, Samehada actually cries for him, not only bestowing the blade with even more lifelike characteristics but also, standing as a testament to the bond shared between the two. Now in B's possession, Samehada kept five of his Supervibrato Lightning Release Swords within it, to better assist him during the events of the Fourth Shinobi World War.

Appearance
Though mostly wrapped in bandages, Samehada's construction is atypical in that its actual blade is comprised from a series of downward facing scales running along the entirety of its length until its hilt, at the base of which is a small skull. Samehada grows larger in proportion to the amount of chakra it absorbs, causing its scales to become so long that they ultimately resemble shark fins and its mouth, located at the tip of the blade, to become even more pronounced. Keeping Samehada wrapped in bandages apparently helps to inhibit this growth to a certain extent.

Personality
Samehada is unique for being a sentient weapon that gains nourishment from the chakra of others and as such, the blade is at its happiest when engorged with chakra that possesses both a distinctive and pleasant flavour. It apparently greatly enjoys Killer B's chakra since, according to Kisame, it tastes like octopus. However, it has shown displeasure towards fire-natured chakra, stating that — according to B — it's far too hot.

Being capable of conscious thought, Samehada chooses its own user, an exclusive process that has often resulted in it being thought of as notoriously picky. If someone it disapproves of attempts to wield it, spikes protrude from the handle in order to force them to release their grasp, at which point Samehada will make efforts to return to its chosen owner. Even if it did betray its former owner for a more powerful wielder, the blade was at least close enough to Kisame to mourn his death.

Abilities
As the blade is made up of scales, it inflicts injuries through shredding or shaving what it comes into contact with, rather than just cutting the object in question. This flaying effect is similar to a shark's skin, hence the sword's name. While it ordinarily remains rigid, Samehada's hilt is able to stretch and bend to great extent, allowing the weapon to be used like a flail.

Samehada shares a symbiotic relationship with its wielder, similar to that of the kikaichū. Although it continually consumes the chakra of its owner, its largest meals come from fights, wherein it absorbs the chakra of the opposition instead. Such an ability allows Samehada to literally slice through an opponent's techniques, in spite of whether the chakra has been transformed or not, and even prevent them from being performed by absorbing all of the necessary chakra, before preparations can be completed. This is particularly useful when fighting jinchūriki, as Samehada can quickly deplete their large chakra supplies as well as remove their chakra cloaks, illustrated when Killer B was reduced back to Version 1 after initially being in Version 2. However, it seems to be unable to automatically absorb ambient chakra, as in all instances where it has absorbed chakra are when either the opponent had a visible aura around them or when direct physical contact had already been established. Due to its voracious appetite, Samehada is drawn to those with large chakra supplies, allowing it to be used as a quasi-sensor.

While the ability to absorb chakra is useful in defeating opponents, it is also beneficial to the user as well. Samehada has the ability to transfer the chakra it has absorbed to the wielder by partially fusing with them, so it can be used to either regenerate injuries or replenish their chakra reserves. This makes the user of this sword extremely difficult to defeat, however, a wielder such as Kisame can take this fusion one step further, by completely merging with Samehada. Doing so causes him to become much more shark-like in appearance, growing fins and webbed hands that allow him to move through water with considerable ease. Kisame also receives some of Samehada's abilities while in this form, such as being able to extend spikes from his body for offence, and absorbing chakra when others come into direct contact with him, as well as the ability to track chakra.

Trivia

 * Suigetsu Hōzuki noted that he wanted to acquire Samehada (along with the other five blades lost to missing-nin) for himself, something he planned to accomplish by defeating Kisame.