Ōtsuka Lōtec No. 7.5 KAI — Stainless Steel | Jumping Hour | Full Set | 2026
Few watches in the world demand as much explanation as an Ōtsuka Lōtec — and fewer still reward the curious as generously. The No. 7.5 is the creation of Jiro Katayama, a self-taught independent watchmaker based in Japan whose entire output across seventeen years amounts to roughly 500 pieces. Distributed exclusively within Japan through a lottery system, pieces reaching the international secondary market are genuinely rare. This is one of them.
The No. 7.5's case architecture takes its cues from 1930s 8mm film cameras — an asymmetrical dial layout featuring jumping hour, minute, and running seconds displays offers a compelling visual rhythm. Three lens-like apertures are positioned across the dial: a custom fisheye lens on the left displays the jumping hour, the largest central window reads the minutes off a rotating disc via a cam-shaped indicator, and a running seconds disc completes the trio. The 40 mm stainless steel case combines straight-grained and sandblasted finishing, measuring 11.2 mm thick rising to 14.8 mm at the lens-like displays. Sapphire crystals with AR coating front and back, see-through caseback, 30 m water resistance. JoopiterMonochrome Watches
Power comes from an automatic Miyota 82S5 with a proprietary module developed by Ōtsuka Lōtec — 21,600 vph, 40-hour power reserve, 26 jewels — driving the jumping hours, rotating minutes disc, and running seconds disc. Every component of the module is designed and finished in-house by Katayama-san personally. The padded calfskin leather strap is purpose-built for this reference, closed by a steel pin buckle. Monochrome Watches
This example was acquired in May 2026 and is brand new, unworn, complete full set.
