**Warning: This article contains spoilers for the latest manga chapters of One Piece**
Fans are still shaken with excitement from last month when Luffy's Devil Fruit awakened revealing that he was actually a Zoan-type user and the successor to Joy Boy.
The lore of One Piece is deep and most of it is still shrouded in mystery. Despite this, there is a great deal that fans should want to know. There's a reason why this series spawns so many theories and why each chapter or episode is held with the highest level of anticipation.
Meito
These are the strongest swords seen in One Piece and the most important to Zoro's character arc. There are several grades in the series, with the highest ranking known as the Supreme Grade Swords. There are currently only four of these known--Yoru (wielded by Mihawk, the world's greatest swordsman), Murakumogiri (formerly wielded by Whitebeard), Ace (formerly wielded by Gol D. Roger), and Shodai Kitetsu (which is said to be the strongest of any of the swords).
Zoro does not currently possess any, however, it is possible for him to turn both Wado Ichimonji and Enma into Supreme Grade Swords by turning them into Black Blades. This seems more than likely and Zoro's current cursed sword, Sandai Kitetsu, will likely be replaced by Kitetsu, a sword that is both the strongest and cursed.
Void Century
This is a mysterious era that takes place over 800 years ago before the events of One Piece. There are no records of this century, thus its name, except for the Historical Poneglyphs. There is something truly horrifying about this century as those who do (and did) know it was reluctant to share and even the World Government forbids any sort of research pertaining to the Void Century.
Robin is desperate to learn more about it, but all we, and she knows is that the notable event during this time is the Great War, though for now, even that is shrouded in mystery.
Haki
Haki is a power derived from within and is split into three types--Armament Haki, Observation Haki, and Conqueror's Haki. Each Haki has its own unique abilities but it's really Conqueror's Haki that stands out. Everyone who has stood on top of the world, or very near it, has possessed Conqueror's Haki. Those who have it are said to possess the qualities of a king.
It is worth noting that two members of the Straw Hats are confirmed to possess it--Luffy and Zoro. This isn't surprising as they both have kingly ambitions. Luffy desires to become the King of the Pirates and Zoro wishes to become the world's greatest/strongest swordsman.
Devil Fruits
Devil Fruits are one of the primary power systems in One Piece and consist of three different types: Paramecia, Logia, and Zoan. While there are many characters encountered in the series that possess a Devil Fruit power, Devil Fruits as a whole are considered rare and are sought after by many people in the world. While these fruits grant the users with incredible supernatural powers, it gives an interesting weakness of the inability to swim.
Why this is is completely unknown, some people believe it's the sea cursing the Devil Fruit user for eating a forbidden fruit. Oda revealed that a certain professor, who many people believe to be Dr. Vegapunk, will at some point reveal the secret of the Devil Fruits. It is worth noting that though Devil Fruits make anyone a powerhouse it does not guarantee someone a conqueror, after all, Gol D. Roger became the Pirate King without one.
Lifespans
Lifespans are one of those tricky subjects in One Piece because it's been said that One Piece characters' lifespan is much longer than it is in the real world. However, there aren't many examples of this. There is Dr. Kureha who is nearly 150 years old and still seems plenty healthy. However, when it comes to other characters in the story, the oldest characters are only in their 70s, like Whitebeard.
However, One Piece characters are no stranger to sickness as seen with Whitebeard and Roger. Additionally, it seems Luffy throughout the series has been placing a large strain on his lifespan. Every time Luffy uses one of his most powerful forms, like Gear 2, it drains some of his lifespan. It's possible this affect occurs when he uses his other gears as well. Oda is often praised for his foreshadowing and this could be one he laid in place as early as Ennis Lobby.
Rocks D. Xebec
Rocks is a terrifying pirate that took both Gol D. Roger and Monkey D. Garp together to defeat. At the time, Rocks was considered the most fearsome pirate of the seas and his crew had three pirates that became Emperors of the Sea--Whitebeard, Big Mom, and Kaido.
Knowing that three of the most formidable pirates fans have seen in One Piece were mere underlings to this pirate is simply chilling to think about. A threat so great that the World Government also saw it necessary to team up with pirates. There is still a lot of mystery around Rocks and his crew and many speculate that he is in fact the father of Shanks, but only time will tell.
Poneglyphs
Of the treasure found along the way, poneglyphs are by far the most important. For Luffy's goal, the most vital poneglyphs are those called "Road Poneglyphs" as these are maps leading to Laugh Tale, the isle that holds the One Piece. If all goes well by the end of the Wano arc, the Straw Hats will have deciphered three of them, leaving only a single one left.
In addition to Road Poneglyphs, there are two other types that come as a pair. "Historical Poneglyphs" reveal the intriguing history of the past and "Instructional Poneglyphs" are used to discover the Historical ones. The only person alive that can read the poneglyphs is Nico Robin, giving the Straw Hats an advantage.
Joy Boy
Joy Boy is a person, or more likely a title held by an important historical figure who amassed and founded the Laugh Tale island and the One Piece. Joy Boy was said to have a second coming and it seems more than obvious that Luffy is officially the next Joy Boy. It's noted in the recent chapters after Luffy awakens his Devil Fruit that Joy Boy has returned.
This means one of two things. Either Joy Boy is the Nika god that Luffy's Devil Fruit transforms him into or that Joy Boy was the previous holder of Luffy's Devil Fruit, the latter seems to be most likely.
The Will of D.
The Will of D. is something mentioned numerous times throughout the series and fans still wonder about the truth behind it. Many characters such as Roger, Whitebeard, Law, and some members of the Kozuki family have known the truth, but fans still don't know. What is known is that they are the enemy of God and that they possess some dangerous fate.
What sort of fate is in store for them isn't entirely clear, but it seems as if those of the family of D. typically cause trouble for the World Government. In fact, Monkey D. Garp is a rare case of a member of the family not being a criminal. The Will of D. carries a strong flame of ambition and it cannot be put out even if that person is killed, for someone else will inherit their will.
The One Piece
The One Piece is a treasure gathered together at a single location called Laugh Tale. Originally it is believed that the treasure belonged to the former Pirate King--Gol D. Roger. However, it turned out that this treasure formerly belonged to an entity known as Joy Boy.
There is still a great deal of mystery surrounding the One Piece, but what fans should know all too well is that the One Piece is indeed real. Whitebeard's declaration still gives readers and watchers chills to this day. Fans can only speculate what this treasure is and for whatever reason, it was enough to make Roger laugh upon its discovery.