Irogami chopsticks – Japanese chopsticks in coloured aluminium from Tsuboe, 10 colours

Tsuboe is a Japanese family workshop in Tsubame, Niigata Prefecture, that has worked metal for four generations – first as a file maker, today as a specialist in oroshigane, the Japanese grater. Tsubame-Sanjo is Japan's centre for metalware and cutlery, and it was here that Kotaro Kasahara began making files in 1907. Through specialised files for the building trade, the teeth of a file gradually became the teeth of a grater, and in 1993 Tsuboe began producing graters in stainless steel, copper, aluminium and titanium. The fourth generation, Shinji Kasahara, has led the workshop since 2010 and in 2021 was named a Niigata Ken-O Meister for his craftsmanship in honmetate.

Honmetate is the heart of a Tsuboe grater. Traditionally each tooth was raised one by one with a chisel, and rather than pressing the entire grating surface in a single stroke as industry does, Tsuboe developed – after hundreds of prototypes – its own NC machine that strikes one tooth at a time with the precision of the hand. The result is a sharp, irregular arrangement of teeth that grates without crushing – less resistance, longer life and noticeably better flavour and texture in whatever is grated. The workshop's motto: one strike, one tooth, one devotion.

From sheet to finished grater, every piece passes through twelve steps in the Tsubame workshop: blanking, flattening, tooth striking, forming, polishing, washing and laser marking, before every single grating surface is inspected under a loupe. The flagship Gokujo – "the supreme" – arrived in 2019 as a stainless steel grater with container and drainage basket, followed in 2021 by two small graters with teeth in eight directions, developed specifically for ginger and wasabi. The sister series SHIRO gathers simple accessories, while irogami – "coloured paper" – is Tsuboe's colourful aluminium series, in which every piece is formed from a single sheet, as if it were folded paper.

The designer behind irogami: Gensuke Kishi

The irogami grater and chopstick rest were designed by Japanese product designer Gensuke Kishi. He began at a design studio in Tokyo, working on interiors, furniture and products. He has since built his own practice in Europe – first in Amsterdam, then in London and today in Rennes, France. Kishi works with local industries and craft traditions across Europe, Asia and North America. His work is about the presence of objects: how material, weight and small irregularities shape the atmosphere of a space.

The irogami hitohira grater ("piece of grater") dates from 2019. It is shaped like a sheet of paper with a turned-up corner that rests against the hand, so you grate directly over the plate. In 2020 the grater received a GOOD DESIGN Award from The Chicago Athenaeum, and today it is also sold by the MoMA Design Store and the museum shop at M+ in Hong Kong. Kishi also won the grand prize in Tsubame's design competition for young designers in 2019 and silver at the Hong Kong Smart Design Award in 2022. He has exhibited at events including Milan Design Week, Ambiente in Frankfurt, London Design Festival and Maison&Objet.

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Related products and collections

• Tsuboe – Japanese graters from Tsubame
• How Tsuboe products are made – twelve steps from sheet to grater

A grater from Tsuboe starts life as a flat sheet of metal and passes through twelve steps in the family workshop in Tsubame before it is sent out into the world. Behind every step lies a simple ambition: to make the finest oroshigane – the Japanese grater – with honest craftsmanship and the best possible sharpness and comfort in use. Read about the workshop's history in About Tsuboe.

Honmetate – the pride of the workshop

Traditionally, every tooth on a grater was raised on its own with a chisel – a technique called honmetate. Tsuboe has held on to it and, after many trials and together with a machinery maker, developed its own NC machine that reproduces the technique and precision of the hand. This precise, complex arrangement of teeth is the foundation of the flagship Gokujo, and the workshop's finest graters have grown out of exactly this technique.

Twelve steps from sheet to grater

1. Blanking

Production begins with each product's shape being punched out of the sheet in a press. Tsuboe works in copper, stainless steel, aluminium and titanium, and every sheet arrives with a protective film on one side. Even at this stage, the workshop takes a series of small precautions to keep scratches and dirt off the metal.

2. Flattening

After blanking, each piece is flattened in a press. It looks like a simple step, but it matters: the smoother the surface, the better the tooth striking that follows.

3. Drilling

Holes are drilled in the handle, and the staff check by eye that they sit precisely, both vertically and horizontally.

4. Stamping

Once the holes are drilled, the company name is stamped into the metal. The piece is now ready for tooth striking.

5. Tooth striking – honmetate

This is where the grating surface itself is created. Most mass-produced graters have all their teeth pressed in a single stroke, while Tsuboe's NC machine raises each tooth on its own. More than any other step, this one determines the grater's sharpness, durability and quality.

6. Forming

The flat piece is shaped in three dimensions in a press with purpose-made dies that add edges, recesses and angles. The dies are designed so they do not damage the freshly struck teeth.

7. Polishing

Polishing evens out differences in colour and small irregularities in the surface, removes burrs from blanking and gives either a gloss or a matte finish. Copper handles can discolour during processing, and this too is corrected here.

8. Washing

Oil, dust and metal residue from processing are washed off. The pieces lie in divided baskets so the grating surfaces do not touch and get damaged, and afterwards everything is checked by eye to make sure it is clean.

9. Laser marking

Depending on the product and material, Tsuboe chooses between stamping and laser marking. The flagship Gokujo series is marked by laser.

10. Final inspection

Every single product is inspected individually, usually under a loupe. The closest attention goes to the grating surface, where even small dents or damage are rejected. At Tsuboe, quality is not only a matter of technology but also of the eyes of experienced inspectors.

11. Packing

The products are placed in cases or wrapped in protective material.

12. Shipping

Even the cardboard boxes are checked for dirt and dents before they leave – a damaged box can take something away from the experience of what is inside.

A workshop that makes room for precision

Care, precision and a strict final inspection call for a well-designed workspace. Tsuboe uses trolleys on castors that spare the body and save needless steps, and a clean, orderly workshop has made the whole production more efficient. A good working environment also brings motivation and room for new ideas – which Tsuboe sees as an important part of building the brand.

Three series – each with its own story

The best sharpness takes time, and Tsuboe's graters are the result of generations of work on functional beauty. To secure the workshop for the next 100 or 200 years, Tsuboe has gathered its own products into three series. The name Gokujo – "the supreme" – expresses confidence in the history of oroshigane and the honmetate technique. Gokujo and SHIRO put sharpness and comfort in use at the centre, while irogami adds colour. Each series has its own role and its own story.

Responsible manufacturing

Tsuboe places weight on manufacturing that takes the environment and society into account. The packaging for all the workshop's own series has been redesigned to remove unnecessary wrapping, and the workshop is gradually moving to plastic-free packaging.

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Related products and collections

• Tsuboe – Japanese graters from Tsubame
• About Tsuboe – the workshop's history and the designer behind irogami

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