The light-powered Citizen Tsuki-yomi A-T Collection

Thirty years ago, Citizen launched the brand’s first atomic timekeeper. Now, to mark that milestone, the Japanese juggernaut is presenting another. The Tsuki-yomi A-T pieces boast the world’s first fully analog moon phase complication for light-powered watches.

While Tsuki-yomi may not be quite as well known in the Western world as they are in their native land, the name of this ancient Japanese moon God is employed here to give this new collection a touch of gravitas. Powered by the Eco-Drive2 H874 caliber, these three new watches combine interesting technical innovations with a full-blooded aesthetic (in one case, quite literally) that befits their significance.

Our take on the Citizen Tsuki-yomi A-T Collection

The Eco-Drive2 H874 is accurate to ±15 seconds per month, is charged by light, and can run for a staggering 2.5 years on a full charge when in power-saving mode. Additionally, the information displayed on these arresting dials, patterned to resemble the surface of the moon, is far from basic. Alongside the time, which is displayed centrally by an hour, minute, and seconds hand, so too can you read off the date (via a window at 4 o’clock), the day (via the hand nestled within the stepped sub-dial at twelve), whether or not it is before or after noon (in your currently selected time-zone) via the dedicated sub-dial at 9 o’clock, and, of course, the phase of the moon through the tasteful aperture at 6 o’clock.

Citizen Tsuki-yomi A-T silver dial reference BY1010-57H
Citizen Tsuki-yomi A-T silver dial reference BY1010-57H

I mention your currently selected time zone because, on top of the standard features, this watch also has a radio-controlled 24-time-zone function. Furthermore, the calendar functionality we have here is far more than a simple weekly mechanism. Rather, thanks to the radio updates this piece receives every day from multi-band radio transmitters positioned around the world to provide (close-to) blanket coverage, the calendar itself is perpetual, adjusting automatically for leap years as well as for the uneven lengths of the months.

Also located in the 12 o’clock sub-dial is a power reserve indicator and an indication to show whether or not the watch is in the northern or southern hemisphere — information that can be displayed upon command but is not shown during normal operation (with the 12 o’clock sub-dial hand relaying the day by default).

Citizen Tsuki-yomi A-T “Blood Moon” reference BY1018-55X
Citizen Tsuki-yomi A-T “Blood Moon” reference BY1018-55X

The hemispheric location of the watch is relevant because, upon crossing the equator, the watch will automatically adjust the view of the moon through the aperture to ensure it is accurate wherever you are in the world.

Having an ultra-accurate moon phase readout that can flip from one hemisphere to another to ensure geographical accuracy is perhaps not top of many watch lovers’ basic requirements list for even a luxury timekeeper, but it must be said that the description of these watches’ functionality alone would be enough to entertain fellow collectors for more than a moment at your next get-together. It is truly fascinating and, given its undeniable esotericism, quite unexpected. The success of a timepiece, however, rests on more than its functionality and while Citizen’s technical achievements here are beyond question, the brand’s biggest achievement might have been making the Tsuki-yomi A-T Collection not just legible, but very attractive indeed.

What stands out about the Citizen Tsuki-yomi A-T Collection

At 43mm wide, these watches might scare some would-be buyers off with their black and white proportions, but the fact the cases and bracelets are crafted from Citizen’s Super Titanium material and are thus lightweight, goes some way to allaying fears that these incredibly clever watches might not be all that easy on the wrist.

Citizen Tsuki-yomi A-T blue dial reference BY1010-57L
Citizen Tsuki-yomi A-T blue dial reference BY1010-57L

They are, however, perhaps surprisingly easy on the eyes. In principle, a dial that is almost entirely covered by a lunar surface pattern sounds at best busy and at worst revolting to my ear, but the execution here is exceptional, with the “Blood Moon” reference BY1018-55X the stand-out model (by far, in my personal opinion).

That is certainly not to say that there is anything wrong with the rich blue and shimmering silver dial options. Both are lovely and very professional and versatile shades. For me, however, the red has such incredible depth and richness, and its divisiveness is so significantly toned down by the pattern (which itself is subtle and nowhere near as obtrusive as one might imagine if reading a simple description of the dial) that it is not just the best of this trio but possibly the most attractive Citizen watch on the market right now.

Citizen Tsuki-yomi A-T “Blood Moon” reference BY1018-55X
Citizen Tsuki-yomi A-T “Blood Moon” reference BY1018-55X

When I dish out such high praise for the aesthetics of a sub-$1K timepiece whose primary claim to fame is its functionality, I really mean to make a statement. Citizen is not a brand I collect. I rarely find myself seriously considering a purchase (perhaps because of my fondness for other similarly priced and positioned watches from Japan), but here I find myself actively drawn to reference BY1018-55X because, as is so seldom the case, there simply isn’t anything like it on the market right now.

For those of you who still feel the red is a step too far for a daily wear, the blue and the silver dials are excellent options, and they are built to withstand a beating. Thanks to Citizen’s proprietary surface hardening technology (called Duractect5), these Super Titanium pieces are scratch-resistant as well as being five times harder, and 40% lighter than stainless steel. Better still, despite the extreme and admittedly niche functionality of these watches, they are water resistant to 100 meters (although Citizen warns you not to operate the crown with wet hands — a slightly over-zealous bit of advice communicated via cutesy drawings that make the instruction manual worth a read).

Citizen Tsuki-Yomi A-T Collection Specs and Price

Reference: Silver dial: BY1010-57H, blue dial: BY1010-57L, “Blood Moon”: BY1018-55X
Movement: Eco-Drive2 H874
Functions: Accuracy ±15 seconds per month (without time signal reception), Radio-Controlled, World Time, “Luna Program” moon phase, perpetual calendar, and luminous hands and indices.
Cases: 43 mm wide, 10.9 mm thick scratch-resistant Super Titanium, water resistant to 100 meters
Dial: Silver, blue, or red
Strap: Super Titanium Bracelet
Price: USD 850


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