Jibuki

Jibuki known also as the Devil's Bliss is an ancient training method/technique that existed before the Void Century. It is passed down on extreme secrecy, because of the sheer simplicity of it's mechanics, as such it is not widely given, but those that know it can easily share it to those most loyal with them, except those that have a Devil Fruit, because to perform Jibuki one cannot have a Devil Fruit.

Overview
Jibuki is a simple concept, it is nothing but breathing techniques that maximize air intake, these techniques were perfected over time and are known to be the best techniques known in the world when it comes to breathing, as such Jibuki teaches it's students how to breathe and nothing else. The effects of the breathing techniques are generally long term and cannot be properly observed in the first few instances but this changes when the second component of Jibuki is added, the diet.

Jibuki is composed of 2 main things, 1 is the proper breathing form, and the second is the proper diet. To use Jibuki to it's full extent one must eat Sea Yeast in any shape or form. Upon consuming the Sea Yeast and performing any breathing technique the person will be instantly rewarded for their dedication to learning the art.

Benefits
Practitioners of Jibuki will instantly be rewarded with the ability to breathe much much better. To a super human degree the user will be able to hold their breath for hours and will be unable to tire out under almost every single circumstance.

Jibuki is a training method that gives the user nearly infinite excess energy that the user may use in their attacks. attacks that require the full power of the user will become spammable.

Furthermore because of the byproduct of Sea Yeast releasing kairoseki like compound those who practice Jibuki over long enough spans of time will be able to naturally negate Devil Fruit users with their touch.

Draw Backs
Because of the special nature of Sea Yeast the user will be absolutely unable to ever use a devil fruit. As such it is impossible for a person to utilize a devil fruit and Jibuki under every circumstance.

However the user may use the breathing techniques, but bear in mind the fact that the breathing techniques are tailored to use in conjunction with the effects of the Sea Yeast, and are otherwise slightly above or the same level of any other breathing technique.