Up for sale is a vintage Seiko 5126-6030 "Sports Diver" or "Rally Diver" watch, for sale as currently running but definitely in need of service, as described further below. The serial number dates it to April of 1969, which is consistent with its usage of the phrase "Water70mProof" on the dial and "Water Proof" on the caseback. Seiko switched to the more accurate "Water Resistant" around 1970, and earlier proof models are generally more prized by collectors. The day wheel on this one is English only (no second language), but it is a Japanese Domestic Model (not surprising, as I bought it directly from Japan), which you can tell by the original bracelet, which is stamped Seiko 5 Sports. JDM watches are generally rarer and thought to be more collectible than their export equivalents. I believe the 5126 sports divers (and maybe the 5126 movement entirely) were all JDM, and I've actually never seen one with a day wheel that shows anything but English.
Seiko introduced a lot of different "Sport Diver" lines, so-called because of their use of the term "Sports" on the dial. These were not true divers, though some (like this one) were listed as water resistant to 70M. They are often big, chunky watches for their time and are generally pretty collectible now. The orange second hand, bold blue "sports" text, and chunky case all give it a very 60s/70s vibe. The 5126 line of sports divers is among the rarest (maybe because they were only JDM? Just my guess), and came with black dials, blue dials, and orange dials. This one is particularly hard to find (compared to the more common -6010 versions) because it is what's commonly called a "Rally Diver" model because of the checkered-flag-reminiscent inner bezel. Both the inner and outer bezels on this model actually rotate - the outer one is a friction bezel you turn with your hand, and the inner one rotates with the crown.
The watch came to me running from Japan, and full honesty I bought it intending to steal spare links from the bracelet - my own example has a short bracelet - but I couldn't get them out, I think because the pins are rusty. So that's the first issue it has. As you can see in the 9th photo, the springbar in the clasp also clearly isn't original as it sticks out too far, and I couldn't get that out either. Perhaps more importantly, after a couple days when I went to photograph and sell this, it wasn't running at all anymore, even after I shook it fairly aggressively. I then took the photos intending to sell it as a complete non-running example. Then, a day later, it was running again - I have no idea why. Maybe there's a loose screw or something inside? Regardless, please bid knowing that, even if it is working now, it certainly needs service or other help to be a reliable timekeeper.
In any case, the hands set as they should, the day and date work as they should, including via the quickset feature for the date (early 5126 models [maybe all of them?] don't have a quickset day), and the inner bezel and outer bezel turn as they should.
Cosmetically, the watch is in OK shape but has some notable flaws, especially the lume on the hour markers and hands, which is very grungy (the lume on the hands is practically black), and the outer bezel has some small bits of black missing in various spots. Please check the photos yourself, but I would say the case shows its original brushed finish well and it certainly hasn't been polished. It's not going to win any beauty contests but it is what I'd call an "honest" example (perhaps charitably). It does come with its original, very funky, sold-link bracelet, which is very hard to find and unique to this model. It is very short, however, and as mentioned above I couldn't remove any links when I tried.
Happy bidding!