Characters that won't come back in one piece

Narrative structure a One piece it ensures that a lot of characters are placed in scenarios where they can return to the story, even after a long absence. That said, even with the opportunities afforded by this structure, there are a handful of characters we likely won't see much of, due to various circumstances. The exact motivations behind each character vary, with most being united only by the fact that the narrative seems to have, for better or for worse, left them behind with no easy way back. These characters have probably already made their last, if not one of their last appearances in the series.

7 Nero

Probably dead

Nero was a member of Cipher Pol 9 (CP9) who only knew four of the six Rokushiki techniques, being untrained in Tekkai and Shigan. Despite being slightly below most of his counterparts, he was able to hold off Franky for a decent amount of time. However, his own relative inexperience led to him being expelled after repeated failures. He was injured by Rob Lucci and thrown into the ocean during a storm known as Aqua Laguna.

There has still been no official confirmation that Nero was killed, leaving open the faint possibility that he may have somehow survived the storm. However, even if that were the case, it still wouldn't translate into further appearances. This is because Nero is fundamentally too unimportant of a character to be definitively declared dead. Maybe he could be reunited at the end of the series with other characters who aren't killed off, but given his immoral nature, likely death, and relative lack of importance, there's little to push him back into the series.

6 Hody Jones

Aged fast

Hody Jones is one of the first serious villains of the Post-Timeskip era One piece. He is the captain of the new Fish-Man pirates and a blind follower of Arlong's ideals, knowing nothing of the people he claims to hate so deeply. He attempts to take over Fish-Man Island by force, which he will use as a springboard to enact a nebulous plan to take over the world. However, for all his talk, he and his crew proved unable to take on even the high-ranking soldiers of Fish Island without some form of support.

To this end, they continuously consumed energy steroids, which would temporarily increase their physical strength. Although this led to premature aging, it gave them more power. However, these steroids not only did not prevent their defeat, but ultimately aged them beyond the point where they could fight. In particular, Hody ate the most steroids and seemed to suffer even more than his peers. They were all imprisoned for their crimes.

5

Given their rapid aging and the larger story's lower focus on the Fish-Man supremacists, there's little reason for Hody and his crew to return properly.

4

3 Enel

The man on the moon

With all the big news revealed during the Skypiea arc, it can't be ignored that it takes place on a completely different terrain than the established blue seas seen in most of the story. This fact can be seen through characters with little investment in the events below, one of which is Enel. This self-proclaimed “God” seems largely content with his takeover, only frustrated by his inability to discover the Fairy Vearth, a legend told by the Birkan people.

After losing against Luffy and more importantly losing his power in Skypiea, he refocused his efforts on finding the Fairy Vearth. As it turns out, this was, in fact, the month. Enel eventually encountered automatons on the moon, who were there to avenge their creator, who died in an alien explosion on the moon. Angry that the aliens were desecrating the Fairy Vearth, he eliminated them himself. After using his electrical powers to revive the defeated automatons, he discovers an army of them underground, as well as evidence linking the sky-dwelling races, and decides to rule the moon.

When one considers its apparent satisfaction with this goal and the apparent lack of people adversely affected by it, Enel seems unlikely to return unless its monthly base somehow comes into play.

2 Jozue

In Hiding

Jozu was a prominent member of the Whitebeard Pirates, being one of the 16 division commanders (notably leading the 3rd Division.) The Devil Fruit allowed him to transform his body into a nearly indestructible diamond at the cost of mobility. Placing it properly could prevent even a powerful slash from Dracule Mihawk, the strongest swordsman in the world, from doing any damage.

However, the deaths of both his captain, Whitebeard, and his teammate, Ace, during the Summit War seemed to spell the end for the Whitebeard Pirates. This was expanded upon during the Payback War, where the remnants of the crew lost to the Blackbeard pirates. Since then, they have gone into hiding, with the locations of most members currently unclear.

It's not impossible for Jozu to return, especially if what ever happened to the other surviving crew members becomes a bit more focused, however there seems little opening for that at present. For now, it can be assumed that he is hiding, although it is not clear where exactly.

1 Gaimon

Guarding Rare Animal Island

Gaimon is a man who fell into a treasure chest and is supposed to be One piece author, Eiichiro Oda's favorite character. This, along with the hair that had grown since then, had given her a strange yet cute appearance. He fascinated Luffy enough to the point where the captain asked him to join the Straw Hat Pirates. Gaimon refuses, being attached to the island's rare animals and feeling an obligation to protect them.

He has since developed a relationship with the future emperor, Buggy, when he was briefly on the island himself. An apparently more permanent resident is Sarfunkel, a woman trapped in a barrel in a manner similar to his own predicament. The two seem romantically involved, due to her nurturing him with affection. The pair were two of many seen listening to Vegapunk's message, but this could be their last appearance. Factors limiting Gaimon's involvement other than his desire to remain on the island include his limited relevance and low combat ability.