When it comes to the biggest secrets of the world of One Piece, fans are particularly intrigued by the National Treasure of Marijoa, which is one of the key elements. It has been briefly mentioned in the story during Law’s battle with Doflamingo, but fans still lack substantial information about it.
However, up until now, many people still do not realize that Oda has been hinting at it for quite a long time in One Piece.

The National Treasure of Marijoa Was Introduced in Dressrosa
The National Treasure of Marijoa was first mentioned in One Piece chapter 761, during the confrontation between Law and Doflamingo. Although fans currently do not know much about it, Oda cleverly hinted at the critical importance of it in the narrative. First, we only need to consider what Doflamingo said about the National Treasure of Marijoa.
Law confronted Doflamingo regarding how to govern, even though he had lost the latent power of a Celestial Dragon, yet he still could utilize immense strength and even manipulate the CP0 agents. Doflamingo revealed something extremely important to Law. According to Doflamingo, the reason why he had this power is that he knows about the existence of a treasure hidden in Marijoa. Doflamingo also emphasized that if this treasure were made public, it would shake the world to its core.
Continuing to speak about this for a long time before, he had the opportunity to use the National Treasure of Marijoa if successful in acquiring the Ope Ope no Mi fruit.
Why Is Imu the National Treasure of Marijoa?

While fans may wonder what the National Treasure is, some might imagine it as a type of supernatural artifact, while the National Treasure could actually be a person, none other than Imu, the figure at the top of the World Government. This idea is entirely reasonable, as Imu’s existence as a monarch would certainly cause global upheaval. The fact that Doflamingo sought to conceal this secret is significant in terms of granting immense power and autonomy to do whatever he wishes.
Furthermore, the Ope Ope no Mi fruit has the potential to help Doflamingo become the King of the World by swapping identities with Imu.
How Could Doflamingo Obtain the National Treasure of Marijoa?
Doflamingo’s plan is quite cunning. He does not desire to become the Pirate King; rather, he aims to control the entire world. First, he wants to seize power to possibly live forever, and afterward, swap his identity with Imu through the Ope Ope no Mi fruit, thereby taking control of the world.

Imu has considerable abilities and has likely used a method to retain power. The Ope Ope no Mi fruit could have been used to grant Imu the gift of immortality, similar to what Ivankov has provided, and afterward, Imu could have also been able to “swap” identities, which is why Oda has always kept Imu’s true identity a secret.