"Black Leg" Sanji, born as Vinsmoke Sanji is the cook of the Straw Hat Pirates and one of the Senior Officers of the Straw Hat Grand Fleet. He is the fifth member of the crew and the fourth to join, doing so at the end of the Baratie Arc. Born as the third son and fourth child of the Vinsmoke Family (Thus, making him a former prince of the Germa Kingdom), he disowned his family twice, once in his youth and again after reuniting with them as an adult. After fleeing the Vinsmokes as a child, he eventually entered the care of Zeff as the sous chef of the Baratie, where he would remain until he met Monkey D. Luffy, who convinced him to join his crew.

His dream is to find the rumored chef's paradise, All Blue, which is where East Blue, West Blue, North Blue, and South Blue meet, along with their wildlife. He is one of the top three fighters of the Straw Hats, alongside Luffy and Zoro. He first gained a bounty of Beli.png77,000,000 for his role in the raid on Enies Lobby. It increased to Beli.png177,000,000 after the Dressrosa Arc, but the condition of his bounty was changed to Only Alive due to his biological father's interference. After he escaped from Big Mom's territory, his bounty condition was reverted back to Dead or Alive, and its value increased to Beli.png330,000,000. Following the Raid on Onigashima, his bounty was increased to Beli.png1,032,000,000. Despite renouncing his surname Vinsmoke, the World Government labels it as part of his name on his wanted poster.]

Under the former Pirate Captain and adoptive father, Zeff's strict training, Sanji has created and mastered a kicking-based martial art referred to as the "Black Leg Style". His legs and feet are extremely powerful, able to smash boulders and effortlessly defeat creatures much larger than himself (like Bananawani and Mohmoo). His legs also imbue him with superior agility, and his speed is close to superhuman as he was easily capable of out-pacing the super fast CP9 members He has also stated that the reason he fights with his feet is that he does not want to risk damaging his hands as he needs them to cook, though handstands aren't prohibited. He is also able to use one-handed handstands, and execute consecutive back handsprings (as seen during his fight with Jabra).

In the same fight Sanji unleashes a new move "Diable Jambe", the power to heat his lower legs to a temperature so high that they glow bright red, by spinning rapidly in place, which causes his attack to be more powerful. After spending two years running away from okama, his sprinting abilities have reached a point where he can momentarily run under water, using a Geppo-like technique he calls "Blue Walk". Not only is he not slowed down by the weight of water as he was during the Arlong Park Arc, but he can run to a degree of incredible speed as fast as a fishman, Usopp has also stated that Sanji's speed is on par with a fishman, who are at their physical prime while under water. He is also able to leap and run much farther than most humans. He has then improved this to using his version of "Geppo" in a move he names the "Sky Walk". Whether or not his proficiency with the technique is on par with other CP9's members still remains a mystery.

Also after the timeskip it's been shown that he can now utilize fire in his strikes similar to his Diable Jambe. This is partially due to the trauma Sanji endured form the last two years, so much so that simply reminding himself of it causes him to burst out in flames through sheer anger. Which he shows after easily defeating the gigantic fishman Wadatsumi, using "Hell Memories" while in this mental state to engulf the massive foe in flames. Due to his innate genetic modifications awakening from his Raid Suit, granting him an exoskeleton, augmented muscles and speed, combined with his own trained Busoshoku Haki. All this lets him use much hotter flames, resulting in the new move, "Ifrit Jambe", making it easier to land powerful blows against even Queen, an Ancient Zoan user who has cybernetic enhancements and Germa 66's own technologies, sending backwards a great distance and making him bleed.