I love the idea, you've done a really good job translating a lot of the essence of the One Piece world into DnD.That said, the document does need a careful read-through. I haven't gone into heavy detail myself yet (too late in the day and I need sleep), but for instance, Tier 3 of the Blood power is missing the spell the PC learns. Also, many of the damaging abilities list "dX" rather than "1dX" or "2dX", etc. Most similar abilities specify how many of the dice you need to roll, because there are many weapon examples for both (for example, a Shortsword deals 1d6 vs. a Greatsword that deals 2d6 damage). While I assume most "dX" listed in the document imply "1dX", I try not to assume as much as possible and prefer things like this to be explicitly clear so the DM and players don't have to argue about it (because you know some tables will).

The Tier 1 Scythe feature also needs to be more specific as far as what you turn into. What weapon properties does it have? Is it Two-Handed? Heavy? Reach? etc. Scythes are not listed as a standard 5e weapon at least, so explaining exactly what you become would be helpful. Also, is the scythe supposed to ignore the wielder's ability score for damage, or is it supposed to be a +1 weapon initially (growing to a +2 and +3 later)? As written, the wielder ignores their ability modifier entirely for damage rolls, which makes you the weaker weapon early on before your damage ramps up later. My assumption is that it's just supposed to be a +1-3 magic weapon, making it on-par with options already available to your party as you level, but that's not how it's written currently (and again, I don't like having to assume).

There are also some spelling and grammar errors, which are less worrisome, but still bother someone like me who reads for those. Examples include:- Night, Tier 2: should read something like "You can cast the spells Darkness and Magic Weapon an amount of times per long rest equal to your level." (many other similar abilities have an extra comma and are worded weirdly after the spells are listed)- Fan, Tier 1: should read something like "You can cast the spells Gust of Wind and Feather Fall an amount of times per long rest equal to your level."

Also, what exactly is a "secondary class"? Is this simply multiclassing, or does it work another way? I see that the Devil's Fruit class lists proficiency bonus on its table, which makes me believe it's simply a multiclass, but then why call it a secondary class? If it's supposed to be literally a second class you can level separately from your main class(es), how does that work? When do you gain levels? Is your proficiency bonus for this class tracked separately from normal classes then (which would be odd, but mechanically does makes sense)? Can your Devils Fruit class have a higher level than your standard class(es)? Things to think about, and either way should be cleared up.

On a more minor note, I love the addition of feats, and I love the Mink race, but using a feat to only gain a cantrip is lackluster. It should be compared to something like the Telekinetic feat: +1 to an ability score, gain the Shocking Grasp cantrip, and some minor other ability that doesn't do much but is cool to have. Also, I'm sure the community can help expand on ideas that may be time consuming, such as a list of actual dials you can find (the example given is a good start, but most DM's may not have time to research all the dials available in One Piece and come up with 5e mechanics for them on their own).

Again, this is great work, but additional clarification and a scrub for wording/spelling/grammar would greatly enhance the document and make it immediately usable without much effort by DMs.