Bought a new Planet Ocean 45,5

Hello,
I have been looking for an Omega Planet Ocean 45,5 for quite some time. Since I don't like the newer shinier models I have been looking for a second generation 45,5mm. Used ones in good conditions also sold very fast and Omega couldn't tell me if there is a store, that has one left.
Last week I saw a new Planet Ocean 45,5 (23232462101005) on Chrono24 from a seller from Japan with a good rating of 4.9 with over 2000 sales. He didn't have the watch in hand, but his replies were fast and good, so I bought it. It arrived yesterday and so far I am were happy with the purchase.
I looked at the comparison pictures between the fake and genuine movement and believe I have received a genuine watch. The warranty card was stamped last week by a big shop in Tokyo, so I should have warranty. The shop in Tokyo offers the same Planet Ocean. On Chrono24 my seller listed the same watch again, it all looks good to me. I am still wondering how two such old models in new condition are available.
From my knowledge, the watch has been produced until 2016 or 17, the serial number starts with 8768. The white paper box says it was manufactured 01/24 and the manual says 1/25, so years after the production date should be. I don't mind I have received a box that doesn't belong to the watch, when the watch itself is legit. I am not an expert, everything besides that seems to be alright, but the manufacturing date makes me wonder.
Is there any way to tell by the serial number if the watch is legit and when it was manufactured?
Should I go to a store that sells Omega and ask them to check if the watch is waterproof, hoping they would notice if it is not legit?
Thanks a lot

It looks fine to me. I don't think there are a lot of fakes coming out of Japan.

I bought my 2531.80 out of Japan and it has become my most worn watch. Along with my Skyfall AT, which I also purchased out of Japan.

The biggest problem with buying from Japan is that many shops are selling watches they don't have in hand. You buy, then they have to buy the watch from a local shop or from a Japanese website. The danger is that you pay and they can't get the watch and have to refund your money. Which can tie up your cash for a week or two. But you've cleared that hurdle so no issues there.

I wouldn't sweat the box issue. The box that was likely issued with the watch originally (the red one) is not very high quality. The boxes they use now are excellent.

The one thing that fakers haven't been able to fake looks fine on yours.