Manufactured by Seikosha, the present watch is an incredibly rare historical relic of the 1940s. Conceived as a pilot's watch, the "Tensoku-Dokei" or "Celestial Watch" is also known as the "Kamikaze" as it was originally worn by Kamikaze pilots in World War II. Not only were very few made, but most examples have all but disappeared, having been destroyed in the wreckage; those salvaged from the embers have been ravaged by the explosions. To discover an example still intact, let alone in excellent condition, is nothing short of extraordinary.

Research from the Seiko Museum shows that this model was produced in two generations. Early examples, such as the present watch, featured a hand wound 19 Ligne movement with 15 jewels and displayed a detailed finishing on bridge and plate. Later generation examples had 9 jewels. The Japanese navy also used these timepieces as a navigation instrument, which could also be worn on the soldier's thigh.