No. 5 KAI

The No. 5 KAI represents one of the latest evolutions from Japan's flourishing independent watchmaking scene, built by Jiro Katayama, a designer who came out of the car and product design world. Before establishing Ōtsuka Lōtec, Katayama worked as an automotive and product designer, spending four years developing references No. 1 through No. 4 to perfect his machining and case-making techniques. In 2012, he released the original No. 5, his first commercially available watch. Unveiled in 2025, the No. 5 KAI reimagines that landmark model with an entirely new display while preserving its unmistakable design language.

What makes the No. 5 KAI ingeniously distinctive is its satellite-hour complication. Rather than relying on conventional 360-degree hands, the watch displays the time using rotating satellites, each printed with four-hour numerals that double as minute pointers. Orbiting on a central carousel, the active hour and minute reading always stays visible along the outer edge.

The case reflects the same unconventional design philosophy found throughout the Ōtsuka Lōtec collection. Measuring 40.5mm in diameter, it features a dramatically domed box sapphire crystal, with the case sides lowered to emphasize the crystal's sculptural profile. While the case itself measures just 7.6mm thick, the crystal brings the overall height to 12.2mm. A partially skeletonized dial offers glimpses of the mechanics beneath, while the Miyota 90S5 automatic movement serves as the foundation for Katayama's in-house developed satellite-hour module.

Like every Ōtsuka Lōtec creation, the No. 5 KAI is produced entirely by hand in exceptionally small numbers from Katayama's workshop in Japan. Distributed primarily through lotteries and waiting lists rather than traditional retail channels, it has become one of the most elusive and sought-after expressions of contemporary independent Japanese watchmaking.