Observation Haki or Kenbunshoku Haki, also known as Mantra on Skypiea, is a form of Haki that allows the user to sense the presence of others, even if they are concealed from view or too far to see naturally. If trained enough, users of advanced Observation Haki can even see slightly into the future
This list is about the strongest Observation Haki Users based on the feats they have shown so far:
#10 – Usopp/Koby
Usopp has awakened his Kenbunshoku Haki during the latter half of the Dressrosa revolt, as he was able to see auras of Luffy, Law, and Sugar, who were in the royal palace, from the old King’s Plateau near the Corrida Colosseum. With this, he was able to pinpoint Sugar’s location and snipe her down from such a distance. Usopp does not yet have control over it as he just awakened it during his attack to knock out Sugar.
During the Whitebeard War, Koby awakened an ability known as Kenbunshoku Haki. Koby was shown hunched over and crying intensely on the battlefield, saying that the voices in his head were disappearing one by one as the combatants around him were slain, much like what Aisa felt during the Skypiea Arc.
After the timeskip, Koby has developed his Kenbunshoku Haki to the point that it is on a very advanced level.
#9 – Vinsmoke Sanji
Kenbunshoku Haki is Sanji’s speciality concerning Haki. During his stay on Kamabaka Kingdom, Sanji has trained his Kenbunshoku Haki to an extremely high level. Sanji’s supreme mastery at using this form of Haki is evident when he dodged a jellybean bullet that was aimed at him by Katakuri. Sanji’s ability to both sense the bullet and dodge it left even the Sweet Commander surprised.
He was also able to dodge multiple bullets being fired at him by Pudding, all from point-blank range.
#8 – Charlotte Katakuri
Katakuri has extraordinary mastery of Kenbunshoku Haki, having trained to such a degree that he can see slightly ahead into the future. Katakuri can use his precognition to increase the accuracy of his attacks to such a degree that Luffy, who is a highly skilled Kenbunshoku Haki user himself, could barely dodge his assaults.
He can use his Haki in conjunction with his Devil Fruit power to great effect. Since he can see slightly into the future, he can predict precisely where an attack will land, allowing him time to dissolve his mochi body out of harm’s way, making it seem as if the attacks simply pass through him. Since he is still technically physically dodging the attack, even attacks imbued with Busoshoku Haki will pass through him without harming him. With this ability, Katakuri is nearly untouchable, and he has stated that it had been years since someone laid a hand on him before Luffy managed to land a hit on him. Katakuri’s Haki can only be nullified if he stops being calm and collected.
#7 – Monkey D. Luffy
Since training with Silvers Rayleigh, Luffy have gained incredible proficiency in Kenbunshoku Haki, allowing him to tell what an opponent intends to do.
While in Totto Land, he strengthened this Haki by battling Charlotte Katakuri, who had mastered this Haki enough to enable him to see a little bit into the future. By the end of their battle, Luffy was able to visualize Katakuri’s next moves extremely well, and develop his Haki enough to dodge many of Katakuri’s attacks and prevent Katakuri from dodging his.
After leaving Totto Land, Luffy has been able to dodge attacks with ease, as shown when he took out a Beasts Pirates scout in Wano Country and soon afterwards dodged multiple strikes from the sumo master Urashima without displaying any effort.
He can now see the future as fluidly as Katakuri, as shown when he helped Hyogoro dodge multiple attacks from Alpacaman and Madilloman before they happened and when he neutralized Babanuki’s attack, having seen a dangerous future.
#6 – Whitebeard
With his Kenbunshoku Haki, Whitebeard foresaw all of Portgas D. Ace’s attempts to kill him, even while asleep, retaliating to each assault and launching the young pirate away great distances, often causing damage to the ship while doing so. In the bay of Marineford, he predicted Crocodile’s sudden attack but did not move, knowing that Monkey D. Luffy would block it. However, due to his age and worsening health, he failed to predict Squard’s betrayal and thus got injured, something which, according to Marco, was totally unexpected from the Yonko.