The Yontsukiryu (四月龍, Four Moon Dragons), are a branch-faction of the Shichibukai created in secret by the Gorousei to counter-act threats specifically within the New World. Their existence remains such a strict and powerful secret that even a Shichibukai can become disillusioned when confronted by the four together.
Who are the Yontsukiryu and what are their responsibilities?
Their original tasks remain the same today as they did when created; oversee the accuracy and disciplinary actions of the Shichibukai of the Grand Line should they rebel, and ensure the Yonkou of the New World do not come into (an) alliance(s). In the event that they should ever fail, or that the Yonkou prove too great to resist, they are to seek out the Ruinade Promos located outside of normal measures.
Since they each ate a piece of the Pseudo Eisei Eisei no Mi created by the Marines technology and replicated to mimic the full powers of the true Eisei Eisei no Mi, the ability of that devil fruit was likewise broken up among them in varying degrees. Instead of one member running through the cycle each of them has been assigned one quarter of the cycle at any given time. It rotates every month between them in a forward progressing motion, so that no one member is stuck in their position.
- New Moon; as the weakest of the group his job is to scout out and investigate.
- Partial Moon; as the second-weakest his job is to relay information and co-ordinate the task forces assigned to them into position.
- Full Moon; at the strongest point he directly engages in combat situations and revises new strategy on the go.
- Crescent Moon; having completed the cycle and preparations for renewal his strength is between Partial and Full Moon, and he oversees the negation of opposing forces from entering the field.
A fifth position is available, however. It has a certain set of restrictions in place for when and how often it can be taken ahold of, but if vastly dwarfs the previous four degrees of strength demonstrated.
- Eclipse; with the full power of the moon directed onto him from the others, his power is quadrupled what it had ever been before. Only after the previous four phases have been cycled through each of the Yontsukiryu once apiece can they directly choose how much of their power will be given to one another again for the next four cycles, OR they may choose to give up all but 1% of their devil fruit abilities to empower a single member for the duration of the full moon.
Former Admiral Kidan once oversaw the Marine post set upon the home island of Kenta Senmaru, and it is in the course of his actions there that saw the destruction of Kenta's uncle's life and reputation per orders higher within the command chain. As a result he was removed from active service and drafted into the newly crafted Yontsukiryu, and thus not only loaths the island but the nephew who has set about hunting down anyone connected to that terrible day.
Roughly ten years ago with the onset of the Shichibukai and the eventual uprising of the Yonkou to power, the Gorousei deemed a fail-safe measure should be implemented to watch behind the scenes incase either group became too much for the then-Marine forces to counteract.
Thus did they choose four men from across the world to do their bidding forth: Admiral Horatio Kidan, Pirate Captain Kemp Oryius, Impel Down Level 6 Prisoner Sayuel Egidou, and as a balancing force Gorousei Offspring Scing Alur.
To keep some degree of authority in check between them all the prized Eisei Eisei no Mi was replicated by the best technology available at the time, and that power was infused into four separate quarters to be given to each of them in altering degrees. Kidan received the greatest slice and began with the most powerful effect, the Full Moon state, while Alur was pushed into the Crescent Moon and the other two as Partial Moon and New Moon respectively.
Kidan was once the Admiral sent to oversee the expidition into the Kinnoku-li Sea and the charting of any available islands. He also happened to be responsible for gathering the pirate force used to raid Kinzoku Jull's laboratory and the ensuing chaos, having relayed all known information on the Axelerator androids meant to protect it and the island in general.