He was  profoundly acknowledged for his extraordinary powers. While most of them remain a mystery, two of them are prominently mentioned in the Manga which are:

Prophecy about Joy Boy:

Based on what was written on the Poneglyphs, Joy Boy would return 800 years after the void century.

Mentions Across The Manga:

1. Chapter 628

In the sea forest, Nico Robin examines the Poneglyph in the forest. She mentions that this is different from the ones she came across up until now. It is written as an apology letter by someone called Joy Boy, she adds. She wonders who that is.

2. Chapter 649

Robin asks Neptune who Joy Boy is. She mentions the fact that she read the Poneglyph in the Sea Forest.  She then asks what was he apologizing for? Neptune discovers and is taken by the fact that Robin can read Poneglyphs. She admits that she is from Ohara. He then agrees to tell her everything about Joy Boy.

As they talk, Neptune says his message was for the mermaid princess living in that time. It was for the promise he couldn’t keep. However, Neptune did not know the details of the promise. The legend says someone will come and fulfill the promise made by Joy Boy. Till then, they had to keep the Noah, the ship of promise safe.

3. Chapter 967

The Chapter narrates Roger’s story. He steals a road poneglyph from Big Mom, meets Franky and Tom and then travels to the fishman island. Roger and Oden both hear noises under water. Roger and Oden see the Road Poneglyph and Poneglyph in the Sea Forest. As they depart the fishman island, they drew closer to Wano. Toki disembarked at Wano with Inurashi and Nekomamushi. They gather thetranscripts from Road Poneglyphs and leave.

Next they head to Zou and find the Road Poneglyph in the Whale Tree. With transcripts from all the four road poneglyphs, they decipher the location of the last island on grand line.  Continuing their sail, they head towards the last island. However, Buggy gets down with fever and he and Shanks stay back. They reach the last island. Roger becomes the Pirate King and discovers Joy Boy’s treasure. Oden documents their journey writing about Void Century, The meaning of D and the ancient weapons. Roger wishes that he lived in the same era as Joy Boy.

4. Chapter 972

Oden, as he boils, states his wish. He declares that he and the entire world is waiting for Joy Boy to arrive after 800 years. When he comes, Wano has to welcome him with open arms and work with him. He requests his retainers to make it happen by opening the country’s borders.

5. Chapter 1014

As Luffy lands in the ocean, Kaido mentions that his conqueror’s haki was crude and he could not be Joy Boy.

6.  Chapter 1040

Momonosuke tells Yamato that Zunesha, the elephant that carries Zou on his back is approaching. He was Joy Boy’s companion when he committed a crime 800 years ago, he adds.

7. Chapter 1044

Zunesha confirms that Joy Boy has returned.

Luffy and Joyboy: How are they Connected?

Luffy’s heart beats like a drum after being defeated by Kaido. He stands up and wonders how he can do that. Additionally, he feels elated. The sound of his heart beat wakes Sanji. Everyone can hear his heartbeat. Nami and Tama cry tears of joy that he is still alive. The 5 elders reveal that they’ve been trying to get a hold of gomu gomu no mi since the beginning. It somehow keeps avoiding them like it has a mind of its own. Furthermore, they announce that Gomu Gomu no Mi is actually a mythical zoan type devil fruit. It is called Hito Hito No Mi, Model: Nika.  The devil fruit gives the power of bring smiles to people far away to the user. He becomes the embodiment of the ‘warrior of liberation’ in addition to becoming rubber man. This devil fruit is considered the most powerful in the world. As Luffy wakes up, he awakens his devil fruit his heart beat being called ‘the drums of liberation’. Zunesha further reveals that ‘Joy Boy is back’. It implies that Luffy is Joy Boy.