You need to go to a professional knife maker, your real pros and have them re-profile the blade. There is more than enough steel there to remove the current edge and grind in a new one, but will need a pro to inspect for cracks or delaminations.

Personally I would be ready to trash it 🙁

Based on my experience this looks to require the removal of a minimum 15mm.

It's never going to be the same, and I really do not have any faith that anywhere you take it could do anything other than destroy it further.

You might be looking at mailing it to a specialty shop.

I would take a breath and move on with life.

I'd also like to share my experience as a home cook that makes everything from scratch, and I have learned that expensive knives are a huge money sink, they always crack or chip, they always end in tears.

I'm rock solidly convinced that a $10-20 German steel chef knife, abused with a sharpening wheel and a hone and replaced frequently is much better in the long run.

You can take an oil stone and just start grinding away until you get it to the shape you want. If you succeed this, I know some saints who need instructions on patience.

Agreeing with Akh; take it to a professional. I've seen videos of people saving knives that looked a hell of a lot worse.

Aight, since you needed to ask, chances are that you can't handle doing it, otherwise you'd be asking what methods to use, right?

But it is possible to DIY that job. It's even possible to do it without losing a lot of the hardened steel, and without majorly changing the profile. I wouldn't advise doing that job as your first effort, but it is totally within the range of skill a beginner can develop with a little practice before starting the actual job.

But, being real, just find a pro.

Caveats: there's very little in the way of proper certification for being a pro. Any rando with enough money to buy a belt grinder can claim to be a pro, and there's not usually any way to prove otherwise or hold them accountable for being full of shit. And, even an actual pro with a decade or more of experience might not know how to handle that steel in a way that keeps full functionality.

Tbh, while I could do it, I'd be shitting bricks the entire time because it isn't exactly something a skilled hobbyist does often. Like, I've done it maybe a dozen times overt the last thirty years, and it was only the last few that I felt fully proud of the results. It's all hand work if you want it done right, mostly. You can use powered tools for some parts of it, but you shouldn't because the faster the tools, the faster mistakes get out of hand and ruin things. Again, I've done this kind of thing, and I still wouldn't want to use power tools for anything but the very first stages. And I'd never, ever use a belt sander btw. Don't trust anyone trying to do so with a heat treated knife unless they have a proper cooling system for their gear. I sure as fuck don't lol

Anyway, mostly useless I guess, but point is that the knife isn't trashed. It did lose life span, no way around that, but it can be brought back to useful

Edit: checked the comments. What you're dealing with is a knife with layers.

There's a core of hardened steel, with a softer steel (though iron is sometimes used) on the sides. The hardened core may or may not extend all the way to the spine, but the typical Japanese knives I've seen don't. Hence the issue with just hogging off metal willy-nilly. You grind down too much, and it isn't impossible to not have any hardened steel left to work with at the kind of angle that a know if that style is really meant to have.

You can see, even in this pic, where the type of steel transitions. I doubt a good pic would show it, but sometimes, you can look at the front of the knife when it's a nakiri and see how much core there is. If it actually extends to or near the spine, there's a lot less issue with just grinding past the chips.

Any story on what caused the chip?

Other than that, just looking up the knife to find out the variety of steel it’s made of. If it’s cheap steel with fancy lettering, this will probably happen again and you should just display it. If it’s not cheap steel, it’s easily worth the cost to fix.

Its steel, and any steel with bad stuff will pass through you before they rust out.

Take a piece of paper and a sharpie or permanent marker. Use the edge of the paper to cover most of the blade and leave the damage part exposed. This will define the new profile. It can go right up to the damage but that does need to be removed. Whether you make the tip quite curved or take it back to try and keep it as straight as possible is up to you.

Now that you have what needs to go marked use a belt sander and hold it long ways and remove everything that you marked. Dunk it in water often to try and keep the temper.

After that you can mark and scribe the new bevel, or you can just wing it. Can probably take the edge down to like 0.5mm with a belt sander than switch back to stones.

It'll be a different knife, better or worse who knows until you use it.

An aggressive reprofile would save it. But I would be worried more bits breaking off, and not just for the rusting, but it could chip or potentially really embed itself into a molar, or it could lacerate your gi lining. I would turn it into more of a show piece if you really want to save it. But I personally wouldn't chance it with food ever again.

Update: Yes it can be saved, thanks for all the helpful tips. Grinded it down with a waterstone to the lowest point of the dent and rounded it off in the front. It cuts like butter and I'm happy to give it another couple cooks at least.

metal file goes brrr