Kenbunshoku Haki, also known as Mantra, is a form of Haki that enables the user to sense the presence of others, yet if they are hidden from view or too far to see naturally.
Haki is a hidden power that is found in every living being in the world. It is not that different from the ordinary senses. However, most people do not see it or fail to awake it.
During the events in Dressrosa, Usopp awakened his Kenbunshoku Haki, Usopp is the sniper of Strawhat Pirates.
Rayleigh is mighty, easily one of the strongest characters introduced.
Rayleigh is highly proficient in Kenbunshoku Haki, able to sense the emotions and nature of others. He could also use it to detect the strength of others on a broad scale. This was shown when Rayleigh used this Haki to sense that there were five hundred animals on Rusukaina who were powerful than Luffy at that time.
As a former part of the Roger Pirates, captain of the Red Hair Pirates, Shanks is recognized to be one of the four strongest pirates in the world.
According to One Piece: Pirate Warriors 3(Non-canon) Shanks can briefly slow his perceived flow of time via quick-thinking-ahead, and often allow him to act sooner by his oppositions’ actions.
Yasopp is described as an essentially unequaled sharpshooter, competent of shooting the antennae off of an ant at one hundred feet away without injuring the rest of it. Luffy also stated that he had never seen him miss a shot.
As a God of Skypiea, Enel had complete control of the island, Enel took this title too seriously.
He can use Kenbunshoku Haki to predict an opponent’s moves shortly before they make them, thereby causing the attack that much more comfortable to evade.
Fujitora is powerful Kenbunshoku Haki user, which he used to counterbalance for his blindness in battle. His unbelievable skill in Kenbunshoku Haki gives him a great sense of danger. He can literally predict fast attacks from opponents such as an unexpected kick from Doflamingo.
Katakuri’s right in the Big Mom Pirates is second only to his mother’s. His bounty is Beli 1,057,000,000 proves that the World Government views him as extremely dangerous.
Katakuri has exceptional mastery of Kenbunshoku Haki, having trained to such a degree that he can see somewhat ahead into the future.