Ever since the first Grand Seiko watch was born in 1960, the pursuit for high accuracy has been fundamental in every Grand Seiko timepiece and innovation. Today, a new and exciting moment in its 60-year history is marked by the introduction of the brand’s first-ever concept creation.

The new creation is a masterwork and true revolution in watchmaking design and fully reveals the Grand Seiko designers’ capabilities and ingenuity. The T0 (T-zero) Constant-force Tourbillon incorporates a fully integrated constant-force mechanism and tourbillon on the same axis for the first time in the world. The constant-force mechanism provides even energy distribution to the escapement regardless of how much the mainspring is wound, and the tourbillon eliminates the error in precision caused by gravity by incorporating the escapement parts and balance in a rotating carriage. These two mechanisms alone require exceptional design and manufacturing technologies, and the integration of the mechanisms as one unit is a patented design that achieves a new level of accuracy for Grand Seiko’s mechanical watchmaking.

In pursuit of the highest level of accuracy for mechanical watchmaking, the designers conceptualised the new creation without restrictions from production capability considerations. The free approach to development resulted in the birth of T0 and inspired essential movement parts for the new Calibre 9SA5, which was developed in parallel with the concept creation.



T0 is displayed on the second-floor lounge of the Grand Seiko Studio Shizukuishi inaugurated on July 20, 2020, in Shizukuishi, Morioka. The rotating tourbillon and intermittent turning of the constant-force as well as the rhythmical 16th note ticking sound of the mechanisms can be thoroughly enjoyed.