GrailAtlasAn independent mechanical watch reference
العربية
Mass-produced#1 in family

Live pricing is coming soon. Get notified when it is available for this reference.

Movement tier: unclassified · caliber Citizen (Miyota) Cal. NH8391: Japanese automatic, 21,600bph, 40h PR, 21j; used in Citizen Tsuyosa; Miyota-manufactured standard automatic movement · 40h power reserve · see-through caseback
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
40 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

Not yet rated

Community + OSINT signals haven’t landed for this reference yet. We don’t publish a rating against zero signal: the number would mean nothing. Editorial body + caliber + market value still surface above; ratings appear once the signal corpus does.

Search pre-owned listings

Chrono24
eBay (sold listings)
WatchBox

Authentication

The sunray dial finish is the authentication anchor; any flat or matte dial is a replacement or counterfeit.

Known issues in the market
  • Sunray finish changes dramatically with viewing angle; a flat matte Tsuyosa dial is a replacement or counterfeit.
  • NH8391 is Miyota (Citizen subsidiary); should be visible through caseback.
AreaWhat to checkWhat is correctRed flag
dialSunray finishVivid, deeply sunray-polished color that shifts dramatically with viewing angleFlat or matte surface; color does not shift with angle; counterfeit or replacement dial
casebackCal. NH8391 designationMiyota NH8391 movement; Citizen subsidiary caliber visible through display casebackNon-Miyota caliber; incorrect caliber for this reference
handsHand finishingHands with correct finish level for this entry-level line; consistent with production standardHeavily scratched or misaligned hands; indicates damage or non-original hands
Common legitimate replacements
  • Crystal; mineral standard on this reference.
  • Bracelet or strap; Citizen OEM preferred.
Expert resources: Citizen Tsuyosa NB1040 press materials. Watchuseek Citizen subforum for sunray finish comparison images.

Authentication guide

Last reviewed June 2026

The Tsuyosa Automatic uses the Miyota-manufactured Cal. NH8391. This is the entry point for Citizen mechanical watches, not an in-house manufacture caliber. The Tsuyosa is a straightforward 3-hand date automatic with no complications beyond the date.

Known reproduction risks

toggle
LOW

The Tsuyosa is not a meaningful replica target at its price point.

  • "AUTOMATIC" text absent
  • Exhibition caseback showing a movement without Citizen-associated rotor branding

Dial variants by era

toggle
EraDescriptionIdentifiers
2021 to presentBlue, black, or green dial with applied markers. "CITIZEN" at 12. "AUTOMATIC" text on dial. Date at 3. Steel case 40mm. Sapphire crystal.
  • "AUTOMATIC" on dial distinguishes it from Eco-Drive variants
  • No "ECO-DRIVE" text anywhere on this watch
  • Applied markers with luminous plots
  • Date window at 3 with no surround ring
  • "SWISS MADE" does not appear; "JAPAN MADE" is the production origin

Service part flags

toggle
Movement

Original: Miyota Cal. NH8391, 21,600bph, 40-hour power reserve, 21 jewels. This is a Miyota (Citizen Group subsidiary) movement, not a Citizen manufacture caliber.

Replacement tells
  • A movement ticking at 28,800bph instead of 21,600bph suggests a replacement movement
  • Rotor without any branding or with ETA rotor markings is not the original NH8391

Case back markings

toggle
2021 to present
  • Exhibition caseback showing the NH8391 movement
  • "CITIZEN" on rotor
  • Reference NB1040-09Z and serial
  • "JAPAN MADE"

Movement tells

toggle
  • The NH8391 beats at 21,600bph (3 Hz), giving a noticeable tick cadence slower than a 28,800bph movement. Three ticks per second is correct.
  • Power reserve is 40 hours. The watch should run at least 36 hours from full wind. Shorter runtime indicates a service need or power cell issue.
  • The NH8391 is hackable (seconds hand stops when crown is pulled) and manually windable. Verify both functions: a non-hackable automatic suggests a different movement.
Sources: Monochrome Watches: Citizen Tsuyosa Review.

You might also like

Tudor Black Bay 58, Navy Ref. 79030N, blue dial, steel case
Tudor
Black Bay
Ref. 79030N
Omega Speedmaster Professional Ref. 310.30.42.50.01.002, black dial, steel case
Omega
Speedmaster
Ref. 310.30.42.50.01.002
Grand Seiko Snowflake SBGA211 Ref. SBGA211, white dial, titanium case
Grand Seiko
Heritage Spring Drive
Ref. SBGA211
Grand Seiko Shunbun SBGA413 Ref. SBGA413, rose dial, steel case
Grand Seiko
Heritage Spring Drive
Ref. SBGA413
Rolex Submariner Date Ref. 126610LN, black dial, steel case
Rolex
Submariner
Ref. 126610LN
IWC Pilot Mark XVIII Ref. IW327011, black dial, steel case
IWC
Pilot
Ref. IW327011

Buying guidance

← Back to Grail Atlas