Seiko Chronograph “Dr. Yellow – Class 923 20th Anniversary Limited Edition” (Ref. 8T63-01E0 / No. 426/5000)

This special edition was released to commemorate the 20th anniversary of the legendary Shinkansen test train "Class 923 Dr. Yellow" —a symbol of Japanese engineering and precision. The model was produced exclusively for the Japanese market and is limited to 5,000 pieces .

This particular example is in new, unworn condition , complete with original box, papers, warranty card, protective films, and two spare links . It is a complete full set , which is extremely rare to find today.

Technical data

• Model: Seiko Chronograph – Dr. Yellow 20th Anniversary (Class 923)
• Reference: 8T63-01E0
• Limited edition: 5,000 pieces (No. 426/5000)
• Movement: Seiko Caliber 8T63 , quartz chronograph (1/5-second measurement, 60-minute counter)
• Functions: Chronograph, 24-hour display, date, tachymeter
• Case: Stainless steel, polished/brushed
• Diameter: 41 mm (excluding crown)
• Height: 12.8 mm
• Lug-to-lug: 47 mm
• Lug width: 20 mm
• Weight: 112 g (including stainless steel bracelet)
• Glass: Hardlex crystal
• Water resistance: 10 bar (100 m)
• Bracelet: Stainless steel bracelet with safety folding clasp + two spare links
• Condition: new, unworn, with protective film, full set
• Origin: Made in Japan

Background: The “Dr. Yellow” – Japan’s legendary Shinkansen test train

The Class 923 Shinkansen , better known as "Dr. Yellow," is a technical masterpiece of Japanese railway history. Since its introduction in 2001 , it has served as a rolling measurement laboratory , collecting data on track geometry, pantographs, signal quality, and power supply during high-speed journeys.

The striking yellow paintwork is reminiscent of maintenance trains from earlier eras and has given the train its nickname. Due to its irregular schedule , seeing the Dr. Yellow is considered lucky in Japan – many railway enthusiasts view it as a symbol of precision, safety, and technical excellence.

To celebrate the 20th anniversary of the Dr. Yellow, Seiko has created this special edition – a tribute to speed, precision and Japanese engineering .

Design and features

• Bright yellow dial in the same color as the genuine Class 923
• Blue chronograph hands and black subdials as a reminder of the train details
• Engraving on case back: “20th Anniversary Class 923 Dr. Yellow” with pull-out contour
• Tachymeter bezel – functional relation to the topic of speed
• Special packaging: yellow anniversary box with train illustration and inscription "20th Anniversary Class 923 Dr. Yellow"

Market and collector valuation

This edition was exclusively available in Japan and sold out completely within a short time. Due to its thematic depth and iconic color scheme, it is now one of the most sought-after Seiko themed models of recent years.

• Rarity: high (hardly available outside of Japan)
• Condition: new / Full Set / with protective films
• Design: a luminous collector's item with iconic color scheme
• Collector's value: increasing – especially in complete, unworn condition

Warranty (used)
This is a used item. The limitation period for claims based on defects (statutory warranty) is 12 months from delivery.