Are there non-breakable weapons?

Based upon the early reviews/previews of Breath of the Wild, it seems pretty clear that at least when starting out, all of your weapons break with repeated use.

However I'm wondering if this also holds true in the mid- to late-game?

For instance, I'd assume based on some of the promos I've seen that the Master Sword exists in the game, and that as a unique and magical weapon that's significant to the plot it's not possible to just break it fighting some orcs (or bokoblins, or whatever). Would that be correct? And are there any other similarly unique, magical, and non-breakable weapons that can be obtained?

If there are non-breakable weapons available in the game, how early is it possible to obtain one of them (I absolutely hate games that foist you with equipment that wears out and breaks, and will happily go well out of my way to avoid having to deal with this mechanic if possible)?

There is 1 unbreakable weapon in the game, but it has a caveat.

The Sword that Seals the Darkness (also known as the Master Sword) is effectively unbreakable. However, while using it, it will eventually "run out of charge" and can't be used for around 10 minutes, but it will remain in your inventory. The only exception to this is when the blade glows Blue. This means it is near enemies that the game considers to be greatly corrupted. While the blade is glowing blue, it has massively increased durability when striking these enemies. However, it will take normal durability damage when striking rocks/normal enemies/etc, even while glowing blue. It's damage also doubles from 30 to 60.

How to obtain it:

You must go to the large Woods shrouded in fog north of Hyrule Castle. Find your way through them (you cannot paraglider in) until you reach Korok Forest. Sitting in the middle of the forest will be the Master Sword. In order to pull it from the pedestal, you need 13 hearts, as pulling the sword out drains 12 and 3/4 hearts. Temporary hearts do not count for this, you need a full 13 red hearts.

There are a couple of other breakable weapons that are infinitely obtainable.

Each Divine Beast you defeat will reward you with a weapon that represents the Guardian who controls the beast. These can all be rebuilt by NPCs in the city where you obtained them when they break. They all require one generic weapon of the same type, 5 flint, and 1 diamond.

Yes

As SGR pointed out, the

Master Sword

is unbreakable. However, there are others.

For one, the

Bow of Light

is unbreakable. However,

it can only be obtained and used during the Dark Beast Ganon fight (without glitches such as Memory Storage, Shield Clip, Extended Shield Clip, or Stasis Clip).

Another unbreakable weapon is the

One-Hit Obliterator from the The Champions' Ballad DLC

but once again, there's a problem:

it cannot be kept outside of the first phase of The Divine Trial (without glitches like Moon Jump Wrong Warp).

Keeping it is pretty much useless, though, as

it only deals 1 damage off the Plateau.

However, it can be hung up for display in Link's house if you just want to show it off.