Model: Seiko Tensoku Dokei “Celestial / Astronomical” WW2 Watch
Year: 1940s
Features:
The Use. Not a pocket watch, nor a wristwatch - Seiko's Tensoku was designed to be strapped to the thighs of Japanese Imperial Naval pilots during World War II. As a result, it’s extraordinarily large for a watch from the 1940s. At 48mm wide, this is not for the narrow-wristed, but it should speak to anyone with a fascination for the past.
The Name. Tensoku (天 [ten] + 測 [soku]) literally means measuring heaven, as the oversized watch was part of the Imperial Japanese Navy Air Service’s celestial navigation kit. Before GPS, pilots charted the skies with little more than a sextant, a reliable timepiece, and the night sky.
The Nickname. But there is a considerably less poetic nickname - the Kamikaze Watch. This is a contentious label, as any direct link to Japan’s Special Attack Units has been considered unproven. The association likely stems from a tendency in post-war Western writing to conflate all Japanese pilots with the Kamikaze missions. It also helps to explain the rarity of this watch, as it doesn’t come up for sale as often as other WW2 watches.
The History. On the morning of May 11, 1945, Kiyoshi Ogawa, a 22-year-old university student from rural Japan, climbed into the cockpit of his Zero. As the Allied push to control Okinawa intensified, Japan countered with Operation Floating Chrysanthemums - a sustained wave of kamikaze attacks on any US carriers. Kiyoshi Ogawa, with a 250kg bomb strapped to the underside of his Zero, picked the USS Bunker Hill as his target.
352 lives were tragically lost in his kamikaze attach, with a further 264 wounded and 41 missing. But Ogawa’s aircraft was not completely destroyed, and amidst the chaos, a U.S. serviceman entered the cockpit and removed his name tags and personal effects.
In 2001, nearly 56 years after the attack, Ogawa’s grandniece received those effects - including his Tensoku watch, making it the first time I've seen proof of its direct association with Japan's Special Attack Unit.
The Engraving. The back of each Tensoku tells its own story. The one of offer today has been engraved with Number 2478 - this isn’t a Seiko serial number, but a military issue marking. It should also be noted that when we compared these markings to other Tensokus engravings, we can see two symbols are missing.
At some point over the last eight decades, someone intentionally scratched off the kanji symbols for Airman. We’d have to speculate as to why someone would want to sever that connection, but turn the caseback over, and you can still see two faint circular indentations where the characters once were - silent evidence of a past erased.
The Stamps. While we’re here, there are two other stamps worth noting. The anchor symbol denotes ownership by Japan’s Ministry of the Navy, and the ト inside a circle shows that the watch was approved for service by the Toyokawa Naval Arsenal - Japan’s largest armament production facility.
The Movement. The movement itself is typical of the era - a nickel alloy construction with nine jewels. While there are no mechanical surprises, it isn’t as industrial-looking as one might expect from a wartime navigational aid. Considered decorative now, Geneva Stripes was originally designed to trap dust particles. Because accurate timekeeping was paramount for a military timepiece, it seems that Seiko did everything it could to help by decorating the bridges and mainspring barrel.
Specifications:
The Condition: In really good condition, considering the age and history. Just serviced. Marks can be seen across the watch, but there is nothing unpleasant or troubling about the condition.
Scope: No box or papers
Movement: Seikosha 9-Jewel Manual Wind
Dimensions:
- Case Width: 48.0mm
- Lug to Lug: 56.9mm
- Case Thickness: 16.6mm
- Lug Width: 24mm
