One Piece's plot is masterfully intertwined, with the major secrets of the series all being connected to each other. The recent chapters have disclosed some interesting details, but rather than giving answers, they raised further questions.
Through the conversation between Nefertari Cobra, the Five Elders, and Imu-sama, One Piece fans were introduced to Queen Lily, who was the monarch of Arabasta more than 800 years ago. Lily was involved with the establishment of the World Government, but, at one point, suddenly disappeared.
Nefertari Lily left a letter which, by Imu's own admission, has fundamental importance to understand the truth that ties the Poneglyphs with the Will of D. and the mysterious events that took place during the Void Century.
Disclaimer: This article contains major spoilers from the One Piece manga up to chapter 1086.
Nefertari D. Lily's letter may be the key to understand the greatest mysteries of One Piece
The connection between Imu and Queen Lily
As recounted in Sabo's flashback of the Reverie, Nefertari Cobra, the king of Arabasta, entered a private audience with the Five Elders to question them about the figure of Queen Lily. An ancestor of the Nefertari Family, she reigned over the country during the time of the Void Century.
Lily was among the founders of the Ancient Alliance, created by the Twenty Kings to fight the Ancient Kingdom, until it was overthrown and erased from the history. The Ancient Alliance then became what is known today as the World Government.
Shortly after the estabilshment of the institution, the monarchs went living at the Holy Land of Mary Geoise, becoming Celestial Dragons. However, Queen Lily refused to do that; she wanted to come back to Arabasta, but suddently went missing.
Cobra addressed that in the books concerning Lily's period there's absolutely no mention of her. He asked the Five Elders for some information, but they answered that they knew nothing. Interestingly, Imu-sama is likely from that time, having survived up to the present day due to the Ope-Ope Fruit's Immortality Operation or some other artifice.
By the way the true leader of the World Government spoke about Lily and the events that happened during her period, it can be assumed that Imu is one of the twenty founders of the Ancient Alliance, or, nevertheless, an individual who was alive at that time.
The Five Elders already mentioned the Nefertari Family (who are now known as D. carriers) as a group of "traitors" for their choice to remain in the lower realm, refusing to become Celestial Dragons, it is now explained that the responsible for such a decision is Lily.
Lily D. Nefertari, Lilith, and the Natural Enemies of Gods
In the Holy Bible, it is said that Lilith, who was depending on interpretations, was either banished from the Garden of Eden for disobeying Adam, or left the mythical place by her own will. In some books, it is written that Lilith did not return to the Garden of Eden because she was seduced by the archangel Samael, also known as Lucifer, the individual who opposed God.
Interestingly, the few One Piece characters who bear the Will of D. carrying the enigmatic initial "D." in their names, have a reputation for being God's Natural Enemies, as devilish individuals who cause major events that change the story.
Obviously, the God concerned is a reference to the Celestial Dragons, who are hailed as "gods" who have created the One Piece world as it is and live in the Holy Land. However, this may be a bigger referral to Imu, who is the highest authority in the world, as even the Five Elders bow down to the former.
By Imu's own words, people with D. were "their" enemies in the past, likely referring as them to opponents to the Ancient Alliance. The greatest representative of those rebels may have been Joy Boy, the legendary individual who lived during the Void Century.
If Joy Boy opposed Imu and the Celestial Dragons during the war between the Ancient Kingdom and the Ancient Alliance, no one more than him was worthy of being considered an enemy to the so-called "gods". It may be that Lily, after joining the Ancient Alliance, met Joy Boy, who led her into having a change of heart and deciding to defy Imu's authority.
After betraying Imu, getting seduced by the the greatest natural enemy of the "gods" of One Piece, and writing a letter to convey information to the next generations, Lily was a loose cannon for the World Government. Thus, she was erased from history, which explains why she doesn't appear in any text.
Queen Lily, Joy Boy, and the Ancient Weapons
As Queen Lily disappeared from the Holy Land but never made it back to Arabasta, she may have traveled all over the world. This may have led into her getting involved with the Ancient Weapons, the legendary items capable of mass destruction, i.e., Pluton, Poseidon, and Uranus.
Pluton is hidden in the ancient submerged city of Wano, while the Poneglyph that bears the information on its location lies in Arabasta's Tomb of the Kings. If Lily was the one behind the plan to hide Pluton, she may have left the corresponding Poneglyph and further information about the Ancient Weapons carved on her empty tomb in Arabasta.
Interestingly, this creates another connection between Nefertari D. Lily and Joy Boy. Like the former left a letter to her successors, the latter wrote a missive to the Poseidon of his time. Unlike the other Ancient Weapons, Poseidon is a living person with the unusual ability to control the Sea Kings.
This power is passed through generations, but not necessarily awakened. It indeed did not manifest itself for countless years, until eventually reappearing in Shirahoshi, the current Mermaid Princess of the Ryugu Kingdom.
During the Void Century, the Poseidon of the time made a pact with Joy Boy -- that when the time would come, she would use her powers to command the Sea Kings to bring the enormous ship of Noah to the surface. However, Joy Boy failed to fulfill his part of the commitment.
As such, he wrote an apology to Poseidon, leaving the message carved on a Poneglyph, and adding that someone would fulfill his promise in the future. This creates a parallel between the messages left by Joy Boy, and respectively, Queen Lily. Moreover, the latter bears a striking visual resemblance to Nefertari D. Vivi, the daughter of Cobra.
There's a significant chance that Lily's message was a reference to Poseidon and that Vivi has read it, or that his father Cobra told its content. This would explain why Vivi is especially kind and protective towards Shirahoshi.
A message of freedom left to the posterity
If Lily met Joy Boy and persuaded him to hide the Ancient Weapons, this would also explain why he left Poseidon in Fish-Man island instead of taking her to the surface as he had promised. After all, the Five Elders were notably enraged by the revelation of Queen Lily leaving a letter that survived until today.
Since its establishment, the World Government has banned reading the Poneglyphs, as they carry essential informations about the events that happened during the Void Century, as well as on the One Piece treasure, which was allegedly left by Joy Boy himself.
As explained by Professor Clover, one of the Ohara scholars, the Poneglyphs were created by people who wanted to leave messages, but feared that paper documents could be erased. According to Imu, Lily played a decisive role in the spreading of the Poneglyphs all over the world, and she most likely did that following a deliberate plan.
Undoubtedly, the message left by the Nefertari Family ancestor is crucial to understand who Imu really is and what is the true story of the One Piece world. When Cobra, right before dying, declaimed Lily's letter, one of the Five Elders yelled to make sure that Sabo couldn't hear the message completely. This further emphasizes its groundbreaking importance.
Final thoughts
When Roger, Rayleigh, Oden, and the rest of the first Pirate King crew visited Laugh Tale, they discovered the meaning of the D., what happened during the Void Century, and what the Ancient Weapons are. Roger then told everything he learned to Whitebeard and did no more, as, for his own admission, they arrived too early.
Right before dying, Whitebeard claimed that the World Government fears the day when someone finds the truth of the world and carry its burden. The ensuing war would threaten the institution's tyranny. For this reason, they tried to erase everything about Roger, including the D. in his name.
The Straw Hats will likely end what the Roger Pirates started. As the second coming of Joy Boy who bears the powers of Nika, the legendary "Warrior of Liberation", Monkey D. Luffy will lead all those who believe in freedom to clash with the tyrannical and corrupt World Government.
Imu and the Five Elders are powerhouses. The former owns a tremendous ability or weapon which can be used to destroy an entire island within seconds. Moreover, it's highly possible that Imu owns some sort of immortality, and the same may be said for the Five Elders.
However, with his fearsome Haki and the unreal powers of Gear 5, Luffy is immensely strong. He can also count on powerful comrades, most notably his right-hand man, Roronoa Zoro, whose strength may one day surpass even that of the legendary "Sword God" Ryuma. Considering also the many allies of the Straw Hats, the final war of One Piece will be amazing.