The Black Leg Style is a martial-arts style that was created by Sanji under training by Zeff. It is designed to free the use of one's hands and prevent them from being damaged during a battle, something that is disastrous to a chef like Sanji or Zeff. As a result, practitioners tend to drop into certain stances in which their upper-body portions are most relaxed, such as placing their hands inside their pockets or crossing their arms together across their chest, and only puts them into action whenever the event requires them to do certain maneuvers such as handstands, which aren't prohibited.
While Sanji rarely takes it to the level that earned Zeff his nickname "Red Leg", he still displays an intense level of attacking power with each kick and the average fighter simply cannot stand up to him. The only prominent times when (one of) Sanji's feet take on the red-color theme is when he uses his Diable Jambe technique. Some of his attacks are powerful enough to rearrange his opponent's face.
As a fighting style, the style boasts a wide and impressive array of kicks, coupled with super acrobatic skill making it a very versatile fighting technique, allowing Sanji to effectively weave continuous and powerful attacks upon adversaries and combine the power of his kicks with his other crewmates respective strengths for devastating team combinations. Most of Sanji's attack names are French words referring to various dishes, though he has recently employed the use of English words when naming his techniques.
- Collier (Neck): A kick to the neck which Sanji does whilst still on the ground. This was first seen as a named attack in a series of attacks against Kuroobi. Collier is the French term for neck meat.