Some specifications:

40.5mm steel case

Miyota base movement with in-house module

Sapphire crystal

Full Set. New. 

Our opinion:

These are the watches that make our hearts beat faster and what we love to have in our space.
The ingenuity, originality and passion put into each piece. 
Jiro Katayama is one of the most talked-about names in Japanese watchmaking in recent years and his creations have gained cult status, having already won some of the most prestigious awards worldwide. 
His next watch, the fourth, will have a price tag of over €100,000, which has made his previous watches even more coveted. 
This self-taught engineer turned watchmaker developed and built the first watches entirely by himself, catching the attention of what is probably the most prestigious Japanese watchmaker, Hajime Asaoka, who made his resources available so that he could build his watches in small productions. 
Unfortunately for everyone on this side of the world, getting an Otsuka Lotec piece is extremely difficult because his watches have an extremely limited production, and for each batch he produces, interested buyers are chosen by lottery because the available units are very few for the number of interested parties. Furthermore, the only people who can enter the lottery are residents of Japan, as the mandatory requirements include the obligation to pay with a local bank card and the watches are only shipped to Japanese addresses.
At this very moment, this is the only Otsuka Lotec N°5 available in Europe. 

Like all creations from this brand, the N°5 KAI has a very industrial, mechanical look and draws attention with some of the solutions used, including the world's smallest bearing with only 1.5mm in diameter. 
Also noteworthy is the incredible sapphire crystal created solely for this watch, which allows it to show all the mechanical splendor of this timepiece. 
This example is from the last batch delivered in Nov 2025, has never been used and, of course, is sold with its complete set of box and documents.