Shark Fin Item Drop Question (SPOILERS)

[The Great Kaio]

So I'm trying to avoid spoilers for the game as much as possible, but I heard that you can get a Shark Fin from a boss drop at one of the bosses in the final chapter(s). I'm trying to craft Ichiban's ultimate weapon, and all I need is the fin, am I able to craft and create Ichiban's Ultimate Bat after beating said boss, or would that not be possible after that?

As mentioned, I'm trying to avoid story spoilers so don't spoil anything with the answers.

[Y8S8]

You can craft the weapon after but Ichiban won't be using it until post-game.

[At@At]

There are multiple sources you can grind shark fins off of in Hawaii. The specific boss you're talking about is past the point of no return for Ichiban though.

[Luxia]

You can try and fish for it in one of the designated fishing spots.

Just be wary - the drop rates are ♥♥♥♥♥♥♥ absurd, I got 3 squid tentacles and a single fin in around 100 catches.

[Loco]

Has anyone dug around in the files to find the loot tables and see if there's any actual difference in locations?

There's a guy that says to fish in the harbor for a 1 in 10 chance at either, but posts a picture that looks like it's on Sakura street lol. https://twitter.com/TheYakuzaGuy/status/1754080420801688027

[Legendary Mr. Tiddles]

I got both fins and tentacles fishing near the north edge of the map in Ijincho, kinda on the western half, if I recall. It may have been close to the batting center.

I'd like to catch live fish sometime though.