Introducing: Tsuki-yomi

The new radio-controlled Eco-Drive watch with automatic moon phase function
CITIZEN presents four new radio-controlled Eco-Drive models under the name Tsuki-yomi (Japanese for "reading the moon"), which are equipped with the world's first
radio-controlled moon phase movement Cal. H874.


Liberation from manual adjustment of moonphase

Moonphase is a traditional function of wristwatch for over 200 years and has been popular among watch fans. While its aesthetics is widely appreciated, its impracticality is often come up for debate. Once the watch stops, it takes time to adjust the moonphase. Tsuki-yomi frees you from manual adjustment of moonphase, thanks to the new Cal.H874. Eco-Drive keeps the watch running as far as there is light. Radio-Controlled function keeps the watch accurate as far as there is radio signal.

How was Tsuki-yomi born? 

The idea came from the Citizen’s profound interest in the space. Since Citizen introduced the world’s first titanium watch in 1970, the brand has searched for the possibility to apply space engineering technology to watchmaking. In 2011, the brand launched the world’s first analog watch receiving time signal emitted from the satellites. In 2020, the sponsorship of the Japanese private space industry HAKUTO-R started.
In 2023, the new timepiece adds another page to the history. 

The “Moon” dial

As the name represents, the dial features the pattern of the moon surface, which is bold yet subtle enough for everyday use. The moon badge on the moonphase window was newly designed to express a sharp and clear outline.



Cal. H874 and the “Moon” dial are housed in the scratch-resistant Super TitaniumTM*2 case and bracelet, completed in a sporty look.
Tsuki-yomi is a perfect harmony of the cosmic motif and Citizen’s advanced technology

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Luna Program – Citizen’s moonphase

Luna Program is the world’s first fully automatic analog moonphase function programmed in the Cal. H874.

Based on a unique mathematical formula, it calculates the phase of the moon each day date signals received from radio transmitters. The phase of the moon at the six o’clock position is then automatically adjusted and displayed. Another notable feature is N.S. Shift. It switches the moonphase display to match the view either from the Northern or Southern Hemisphere.

The name Tsuki-yomi

The timepiece is named after the ancient god of the moon in Japan. It also means “reading the moon.” The name fully expresses the modernity and craftmanship tradition both of which are deeply rooted in the Japanese culture. 

BY1010-81H Tsuki-yomi
BY1018-80E Tsuki-yomi
BY1010-81L Tsuki-yomi
BY1018-80X Tsuki-yomi