The Ōtsuka Lōtec No. 9 is a Japanese mechanical watch built around a visible display of moving parts. It combines jumping hours, rewinding minutes, a tourbillon, an hourly gong and a power-reserve indicator. Rather than using conventional hands, it shows the time on two disks beneath sapphire crystal, with a hammer striking a pipeline-shaped gong at each hour.
What is the Ōtsuka Lōtec No. 9?
The No. 9 is a manually wound wristwatch designed by Jiro Katayama. Its five stated functions are jumping hours, rewinding minutes, a tourbillon, hour-striking and power-reserve indication. The design makes the mechanisms part of the display: the brand presents the movement and its textures beneath sapphire crystal as an industrial-looking mechanical scene. Ōtsuka Lōtec announced the watch’s completion on September 22, 2025. The official No. 9 page lists the functions and specifications, while the completion announcement gives the dated milestone.
How do the time display and gong work?
Jumping hours and rewinding minutes
The time display sits on the right side of the dial. The upper disk shows the hours and jumps to the next hour; the lower disk shows the minutes, moving across its scale before a hairspring at the top of each hour returns it to zero. The maker compares the minutes disk’s return to the motion of an analog body-weight scale. A luminous block beneath the disks illuminates their numerals in low light, and a slim indicator shows the remaining power reserve.
The hourly strike
At the hour, the jumping-hour and rewinding-minute mechanisms act, and a hammer strikes a pipeline-shaped gong on the left side of the display. Ōtsuka Lōtec describes the resulting sound as industrial. This is an hour strike, not a claim that the watch chimes continuously or plays a melody; the maker’s description and specifications are on the official model page.
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- CLASSIC WHITE DIAL WITH BLUE HANDS – Clean white dial with striking blue hands and bold Arabic numerals for easy reading at a glance. Vintage-inspired design that draws compliments. A timeless aesthetic that works equally well for business or casual wear. 40mm case size offers substantial wrist presence without being overwhelming
- AUTOMATIC SELF-WINDING MOVEMENT – Powered by wrist motion during wear, no battery needed. Manual winding available as backup for occasional use. For optimal performance, wear regularly or hand-wind 15-20 turns daily. Note: Power reserve may not last overnight without regular wear or winding
- SCRATCH-RESISTANT MINERAL GLASS – Reinforced mineral crystal resists scratches and scuffs from daily wear. Clear exhibition case back lets you view the intricate mechanical movement. Durable construction for reliable everyday use
- COMFORTABLE BROWN PU LEATHER STRAP – Soft, flexible PU leather strap designed for all-day comfort. Adjustable buckle closure fits most wrist sizes. 20mm strap width complements the classic dial design. (Note: For extended durability, avoid prolonged exposure to moisture.)
- VERSATILE & EASY-TO-READ DESIGN – Bold numerals and contrasting blue hands ensure quick time reading in various lighting conditions. 13mm slim profile fits comfortably under shirt cuffs. Ideal for work, weekends, travel, or casual outings. 3ATM splash-resistant for hand-washing and light rain
What movement is inside the No. 9?
Ōtsuka Lōtec identifies the manually wound movement as its newly developed, in-house Cal. SSGT. The name refers to the movement’s layered complications, which the maker likens to sushi arranged on a sushi geta. The specifications published by the maker are:
| Specification | Maker-listed detail |
|---|---|
| Caliber | Cal. SSGT; manual winding |
| Components | 278 |
| Jewels and bearings | 30 jewels plus five ball bearings |
| Frequency | 18,000 vibrations per hour (2.5 Hz) |
| Power reserve | Approximately 40 hours |
| Movement dimensions | 41.3 × 26.4 mm; 10.35 mm thick |
| Balance | Free-sprung |
| Other construction detail | Some parts, including the barrel, are from Cal. 6498 |
The maker says MinebeaMitsumi produced custom 2.5 mm ruby ball bearings for the watch and describes 1.5 mm ball bearings as the world’s smallest. Those supplier and superlative claims are Ōtsuka Lōtec’s statements; the specifications are available on its No. 9 page.
What inspired the design?
Katayama says he wanted a wristwatch like an induction electricity meter, with mechanical components visible and moving beneath a transparent cover. In his words: “With № 9, I wanted to create a watch where every moving part under the sapphire crystal gives off the feeling of industrial machinery — its textures, vibrations, and sounds.” This is the designer’s account of his intent, not an independent assessment of the watch’s performance. The quotation appears on the official No. 9 creation page.
Ōtsuka Lōtec’s account of Katayama’s career says he worked in automotive design, later became a freelance product designer, acquired a bench lathe through an online auction and began making watches around 2008; the brand says he began selling watches in 2012. Its design statement emphasizes tactile metal objects and details such as screws, knobs and levers. These biographical and design details come from the brand’s own account.
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- Material: Mechanical movement, mineral strengthened glass mirror, the case is made of stainless steel and the strap is made of High grade leathe.
- Measuare: Band length: 18.5cm/7.39inch, dial diameter: 41mm/1.6inch, dial thickness: 15mm/0.6inch.
- 30M waterproof, Daily waterproofing to prevent water splashing. But not suitable for bathing and swimming.
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- It will be a wonderful gift for your father, husband, friends, son or brother on some special days.
Case size, strap width and water resistance
The case measures 48 mm tall, 30 mm wide and up to 13 mm thick. It is made of 316L stainless steel, has a sapphire crystal and solid back, and is supplied with a calfskin strap. The listed lug width is 26 mm. That width is a starting point when looking for a replacement strap, not confirmation that every nominally 26 mm strap will fit: attachment style and clearance also matter, so confirm those with a seller or watchmaker.
Ōtsuka Lōtec lists water resistance at 3 ATM. That is the maker’s stated rating; it does not establish suitability for swimming or another specific water activity. The watch is listed as made in Japan and comes with a one-year warranty. The official specifications are the source for these details.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Price and purchase context
The official No. 9 page displays a price of ¥17,600,000 including tax, or ¥16,000,000 before tax, and lists a one-year warranty. These are the maker’s displayed figures; current stock and sales terms are not established by the listing. Check the official page for the current price and purchase information.
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