Grand Seiko releases the Kodo Constant-Force Tourbillon to mark the company’s 141th Anniversary

The Grand Seiko Kodo Constant-Force Tourbillon marks a new milestone in the sixty-two-year history of the Japanese brand

Legendary watchmaker Kintarō Hattori established the company that would become Seiko back in 1881 and then continued to lead it until he passed away in 1934 at the age of 73. Fast forward to 1960 and Grand Seiko was established. It would then become the best expression yet of Kintarō Hattori’s philosophy that his company should be “always one step ahead of the rest. This year, as the company celebrates its 141 anniversary, the storied Japanese brand released its very first mechanical complication watch named the Grand Seiko Kodo Constant-force Tourbillon. Kodo, named after the Japanese word for heartbeat, amazingly combines a tourbillon and a constant-force mechanism as one unit on a single axis. This marks the very first time such a combination is done in horological history.

Even at a glance, the Grand Seiko Kodo Constant-force Tourbillon truly showcases the charm and beauty of its dial architecture. With its unique appearance when in motion and with its carefully designed sound, this revolutionary watch reveals its vitality both audibly and visually, thanks to the open-work design and the sapphire case back. The intricate details of the watch are fully supported by both Platinum 950 and Grand Seiko’s Brilliant Hard Titanium for the case in order to achieve a long-lasting beauty. Furthermore, to ensure that a visually pleasing harmony is revealed from every angle, some case parts of both materials are Zaratsu-polished and others are completed by hand by highly skilled craftsmen. Grand Seiko’s expertise in hand polishing is certainly evident in the way that both materials’ surfaces are perfectly harmonized.
On the other hand, as mentioned earlier, one of the most remarkable aspects of this new watch is the way that the constant-force mechanism and the tourbillon have been integrated to allow the creation of an overall design that is perfectly in harmony with the values of Grand Seiko. It’s clear that the integration of the two mechanisms allows optimum use of space, which can be seen from the front side of the watch.

Back in 2020, Grand Seiko introduced the T0 Constant-force Tourbillon, a concept movement that incorporated this patented mechanism. To bring the concept to life in a finished watch, each and every one of the 340 components of the caliber was re-examined and, where necessary, re-designed and re-engineered for production by a team that’s entrusted with the assembly and finishing of the movement and the case.
The result is the Caliber 9ST1, which is not only smaller than the concept movement but also maintains its high accuracy at a stable rate for longer thanks to the constant-force mechanism. The Grand Seiko Kodo Constant-force Tourbillon is driven by this particular caliber, which is complex in its engineering and design, but is based on the simple insight that the integration of a constant-force mechanism and a tourbillon as one unit on a single axis would deliver practical benefits. Mind you, the integration of the two mechanisms creates a dazzling visual effect. The inner tourbillon carriage rotates smoothly as the balance steadily vibrates at 8-beats per second and the outer constant-force carriage follows its rotation at exact one-second intervals.
On the other hand, the sounds of the escapement and of the once-per-second impulse of the constant-force mechanism also harmonize with this regular visual rhythm to create, for both the eye and the ear, a deeply satisfying and 133 reassuring heartbeat. On that note, the sapphire crystal case back from the watch magnificently reveals the beauty of the movement’s finishing and its intricate construction.

To top it all off, the watch is also offered with a calf strap specially treated in the same traditional way as was used to create the high-durability material once used in the armor of the samurai. The strap’s surface is painted by hand with Urushi lacquer in a multi-coating process that gives the strap a delicate sheen, while it also comes with an alternative crocodile strap.
While this remarkable watch is in every way a new departure for Grand Seiko’s watchmaking, the practicality for which Grand Seiko is renowned is still fully realized in every detail, along with the very stable accuracy of the movement. As the brand’s first mechanical complication watch, the Grand Seiko Kodo Constant-force Tourbillon is an amazing combination of the refinement and technicality that has become synonymous with Grand Seiko.