One Piece : The Journey of the Flash

Minato's future development:

Devil Fruit:

1. Evil sealing method - Place a cursed mark (Created through hand seals) on a talisman or on a surface to suppress the person's physical strength. Unable to fully suppress a person stronger than the seal. to remove the seal, a person requires Armament Haki to shield against the seal's impact on skin, or Observation Haki to dodge.

2. Haki seal (Like Tsunade) - Created to constantly store physical strength and later on Haki and for it to release the said amount of Haki/Physical Strenght, with this technique by break the seal and pumping the stored chakra back into the user's body to increase strength for a short period of time. Can only store 10 days worth of Haki. Weakness and affected lifespan after usage.

3. Drain Seal - Stay in physical contact with an opponent to absorb stamina and physical strength. Only during contact with an opponent.

4. Flying Thunder God - Manipulate space between two seal points or user and seal. can be used for instantaneous teleportations, or sending attacks elsewhere. also can permanently mark opponents if Armament Haki is not used. Uses energy depending on the distance. Has a bunch of marked 3 pronged kunai.

5. 4 Seal Barrier - creates a barrier between 4 seals placed in the shape of a square.

Fighting Style:

1. Water Stream Rock Smashing Fist: When in use, a blue aura can be seen around the user's extremities. and Water Stream Rock Smashing Fist parallels real-life Tai Chi. It has the unique nature to return the opponent's attacks at double the damage. Stacks up damage while performing combo attacks.

2. Flash Step: Silent Soru

3. Afterimage clones: move at fast speeds to create clones and then move between them.

4. Hirudora: A powerful Haki-infused kick that looks like a white tiger, it creates intense air pressure and can be used as a long-range attack.

5. Basic Swordsmanship: Using kunai to target vital points, stabbing and slashing movements.

6. Air pressure Machine Gun: able to use air pressure thrusts from the tip of a kunai or weaker version from fists like a machine gun continuously.

Haki:

Basic Armament (Chinjao Level)

Future Sight (Wano Luffy level meaning a bit worse than Katakuri)

Conquerors Coating (Unable to sustain for long)

P.S

Love Interest is probably Robin, no harem.

Also this is an AU so although he will join the straw hats, the challenges and and enemies may be stronger and also different and will join around Enies lobby or Skypia arc.