Kurono Tokyo Launches its First Diver, a Two-in-One Watch with Sealed Outer Case

When you think about Kurono Tokyo, the side-brand of Japanese independent watchmaker Hajime Asaoka, you should picture something compact and elegant in your mind. Watches often focus on traditional crafts, with restrained cases and classically Japanese. The sportiest models the brand has ever created were mid-century-styled chronographs. Well, this is about to change as Hajime Asaoka has decided to give the dive watch its own vision. And instead of creating just another dive watch, he has designed something a bit more special with the Kurono Diver.

In the words of the brand’s founder, the Kurono Tokyo is a watch that “reconsiders the conventional architecture of a diving watch.” Instead of creating a watch for diving, Hajime Asaoka created a classic watch with 50m water-resistance, which also happens to be the brand’s first cushion-shaped model. Doesn’t sound exactly like a watch for aquatic activities, right? Well, here’s the catch. The box also includes a purpose-built diving case, allowing the timepiece to transition seamlessly from a compact, almost dressy watch to “an instrument for recreational diving.” Indeed, with the Kurono Diver, you’ll get a watch, two straps, an outer case and a tool to seal it. Two-in-one, for two very different wearing experiences.

Let’s start with the base, the actual watch. As said, it’s Kurono’s first cushion-shaped watch… And it’s a small one, measuring 35mm x 35mm, with a slender profile of 9mm (incl. the sapphire crystal) and a lug-to-lug measurement of only 37.4mm. It was deliberately designed in such compact proportions so the watch could fit in a (sort of) reasonably sized diving case. The watch itself, due to its shape and the white dial with oversized luminous markers and blue steel cathedral hands, almost has a mid-century military vibe. Inside the case is an outsourced automatic movement by Miyota, the calibre 90S5 time-only running at 4Hz and boasting 40h of power reserve.

But then, there’s more to the Kurono Diver as you can imagine. Remove the leather strap from the cushion-shaped watch head, thanks to quick-release spring bars, and then the “magic” happens. The watch head can now be inserted into an external sealed diving case that drastically changes the look and function of the watch. Why do it this way? Well, as Asaoka-san explains, “the crown has always been the Achilles’ heel of diving watches. To address this, various innovations have been employed – from screw-down mechanisms to locking levers. Yet, the ultimate solution is to eliminate the crown entirely. Thanks to the high winding efficiency of modern automatic movements, a watch worn regularly rarely stops and maintains excellent precision. Once the time is set, the need for crown manipulation is virtually non-existent. It was this realisation that inspired my concept.”

Thanks to the provided tool (you can see how it operates in the video above), you simply open the outer diving case and place the watch head into it. Then, to encapsulate the entire wristwatch within it, simply close it again. The bezel functions as a threaded lid and can be easily unscrewed counterclockwise. This doesn’t remove the classic and essential unidirectional rotation mechanism of the bezel, which can be used as any other diver’s model, to track elapsed time while preventing the case from accidentally loosening.

The outer case is not the smallest, as you can imagine. Also made of polished steel, it measures 46mm in diameter with a L2L of 56.7mm and a thickness of 13.5mm. It features a sapphire crystal, and the bezel, with its 60-minute scale, is made in deep red Extra Super Duralumin. As far as I understand it, the case has two depth ratings. For lighter use, the case can be opened or closed by hand without the tool and then rated at 100m water-resistance. When using the tool and carefully tightening the bezel, then the watch transforms into a professional instrument capable of withstanding depths of up to 300 meters. This outer case comes with its own rubber strap.

Availability & Price

The Kurono Diver (including the watch head, two straps, the outer diving case and the dedicated tool to seal it) is released as a limited production model, without mention of the numbers by the brand. It will be available worldwide through an allocation-via-ballot system, where potential clients should express their interest on the brand’s website from March 5th to March 11th. It must be noted that applicants with recreational (or higher) diving certifications (e.g., PADI, SSI, NAUI, etc.) will be prioritised. A strict one-watch per customer policy is also applicable.

Once applications are received, the Kurono team will review applications and allocate pieces via ballot (details are indicated on the watch’s page). The Kurono Diver is priced at USD 2,700, excluding taxes and potential tariffs for exports to the US. Deliveries are expected from May 2026 onwards. For more details, please visit kuronotokyo.com.