The Buki Buki no Mi is a Paramecia type Devil Fruit that gives the user the ability to change their body parts into weapons, which lets the user become a Full-Body Weapon Human (全身武器人間,Zenshin Buki Ningen?). It was eaten by Baby 5.
The Buki Buki no Mi gives the user the ability to change their body into any kind of weapon. The user can either transform small parts of their body, like the fingers, hands or arms; or a larger body-section, such as their entire torso or even their whole body, into a weapon.
While transformed into a weapon, the user does not take any damage inflicted as a result of the weapon's impact, such as detonating while in the state of an explosive. If the user's body is broken apart as a result of the weapon's intended effects, the pieces can easily reform into the user's full body, undamaged, akin to a Logia. However, this Logia-like regeneration does not apply to the user's human form, even if the user is partially transformed.
Although transforming into self-detonating weapons, such as missiles and bombs, does not harm the user, the user remains vulnerable to the generated weapons if they are aimed at oneself, voluntarily or otherwise, such as when Doflamingoforced Baby 5 to point her own finger pistol at her head, or when Baby 5 pointed her own musket arm at her head after Sai asked her to kill herself. Other than that, this fruit is weak to the standard Devil Fruit weaknesses.
Befitting her occupation as the crew's assassin, Baby 5 uses this fruit's power for assassination and combat at both long and close range. She can transform both small individual parts of her body like transforming her finger into a gun, and she can also turn half of her body into a sword or even transmute her entire body into a rocket or explosive. For the most part, however, she usually transforms her arms, and in lesser occasion legs, into either various types of blades or firearms to complement hand-to-hand combat. Partnered with Buffalo and his rotational ability, Baby 5's weapons can gain an increase in momentum and damage range.
Buki-morphose (武器変貌（ブキモルフォーゼ）,Bukimorufōze?, literally meaning "Weapon Metamorphose"): Baby 5 transforms part of her body into the weapon that she wants to be. In the Viz Manga, this is called Arms-morphosis and in the FUNimation subs, this is called Weapon-morphosis.
Espada Girl (剣女（エスパーダ・ガール）,Esupāda Gāru?, literally meaning "Sword Girl"): Baby 5 turns into a large sword, while her legs serve as the handle. It is strong enough to cut Franky's General Shield in conjunction with Buffalo's rotational abilities. "Espada" is the Spanish and Portuguese word for "sword".
Missile Girl (ミサイル女（ガール）,Misairu Gāru?): Baby 5 turns into a large missile; Buffalo then uses his "Guru Guru Toshaho" to launch her; this only provides her the additional momentum, as she can move on her own. This combination was first used against Franky. It caused a huge explosion that toppled Franky Shogun but otherwise caused no damage to it. After impact, Baby 5 is blown to pieces and she reforms from those fragments unharmed. Baby 5 called the effect of this attack "flaming passion".
Revolver Girl (拳銃女（レボルベルガール）,Reboruberu Gāru?, literally meaning "Pistol Girl"): Baby 5 turns into a giant gun barrel and fires rapidly. This was first used against Franky Shogun but dealt no damage.
Sickle Girl (鎌女（シックル・ガール）,Shikkuru Gāru?): Baby 5 transforms herself into a kusarigama-like weapon, with her arms combining together to serve as the chain and the legs together into a massive sickle, allowing her to be spun around and used by Buffalo. It was first used against Franky, where their combined attack was strong enough to pierce Franky Shogun's armor.
Gatling Girl (ガトリング・ガール,Gatoringu Gāru?): Baby 5 transforms her right leg into a Gatling gun and fires it rapidly. It was first used on a subordinate for laughing at Pica's high-pitched voice. This technique has yet to be shown or named in the manga, but was introduced on the cover of volume 70.
Revolver Leg (拳銃脚（レボルベルレッグ）,Reboruberu Reggu?): Baby 5 transforms her leg into a firearm, shooting her targets at the same time as a kick. It was first used on a subordinate for laughing at Pica's high-pitched voice, and named when used against Dagama.
Buki-morphose (武器変貌（ブキモルフォーゼ）,Bukimorufōze?, literally meaning "Weapon Metamorphose"): During the battle with Franky Shogun, she demonstrated extra transformations not seen in the manga.
Flying Disk Girl (フライング・ディスク・ガール,Furaingu Disuku Gāru?): Baby 5 transforms into a spinning top and allows herself to be thrown at the enemy by Buffalo at high speed. The attack was easily deflected by Franky Shogun's Franken.
Fire Girl (ファイア・ガール,Faia Gāru?): Baby 5 transforms her upper body into a flamethrower. The effectiveness of the attack can be increased by Buffalo creating a gust to fan the flames, increasing their spread and ferocity, but it was still not enough to harm Franky Shogun.
Besides from them, Baby 5 transformed some of her body parts to different weapons but she did not give them a name. Unlike "Buki-morphose", these transformations are limited to small parts of her body.
Baby 5 ate the Buki Buki no Mi around age 8-10, or possibly before that, as she used the ability against Wellington.
The Buki Buki no Mi has similarities with other Devil Fruits due to its weapon-producing capabilities, specific types of weapons that such other fruits are more focused on:
It is similar to the Baku Baku no Mi, as they both allow the user to turn their bodies into weapons; the main difference is that the Baku Baku no Mi is limited to the weapons the user devours, and has up to twenty-four hours until the weapon is fully digested, while Baby 5 can morph into any type of weapon at any time.
Certain Paramecia are mistaken for Logia. The Buki Buki no Mi falls into this category, as it allows the user to produce and become something. In this case, it also provides a form of regeneration based on the chosen transformation. However, weapons are not elements, so it cannot be a Logia.