Partial Designs and Related Designs in Japan: How to Protect Key Features and Variations

"A competitor copied only the handle of our product — can we stop them?" "We registered one design in Japan, but now a copycat sells a slightly different version." "We plan several color and shape variations — do we need a separate registration for each?"

Overseas manufacturers and cross-border sellers ask us questions like these all the time. The answer usually lies in two tools of Japanese design law: partial designs and related designs. In this article, Japanese Patent Attorney Toru Kano of BrandAgent explains what each system protects, how they differ, and how to combine them into a filing strategy for Japan.

*Official fees and rules are those published by the Japan Patent Office (JPO) as of November 2026.

Why one design registration is often not enough

A standard Japanese design registration protects the appearance of the whole article — its shape, pattern and color as a whole. The right covers designs that are identical or similar to the registered one.

Copycats know this. A common tactic is to keep the distinctive feature of your product — a characteristic grip, a unique nozzle, a recognizable front panel — and change everything else. If the overall impression becomes different enough, the product may fall outside the scope of a whole-product registration.

Your own product line is also rarely a single design. You probably sell sizes, shapes and minor variants. One registration cannot reach variations that fall outside its similarity range.

Partial designs address the first problem (protecting the feature), and related designs address the second (protecting the family of variations).

Partial designs: protecting a distinctive part of the product

A partial design registration protects the appearance of part of an article. In the drawings, the part for which protection is sought is typically drawn in solid lines and the rest of the article in broken lines, so it is clear which portion is claimed.

Typical candidates for a partial design

• Handles and grips: cup handles, tool and kitchenware grips
• Control and display areas: control panels, button layouts of appliances
• Tips and openings: pen tips, nozzles, container necks
• Signature elements across a series: a feature you use on many different products

What to keep in mind

Similarity of a partial design is assessed not only on the shape of the claimed part but also on its position, size and extent within the whole article. A partial design does not automatically cover that shape wherever it appears.

Deciding how much to draw in solid lines is the key strategic choice. If the claimed part is too small or too simple, it may be refused as lacking novelty or creativity. If it is too large, a copycat may avoid it by changing just one element. This is where careful drafting by a Japanese patent attorney makes the biggest difference.

Since the April 2020 amendment, partial designs are also available for sets of articles.

Related designs: protecting a family of variations

Normally, if two similar designs are filed, only one can be registered. The related design system is the exception: an applicant can register designs similar to its own earlier design (the principal design) as related designs.

Each related design is an independent right that can be enforced on its own, and its scope extends to designs similar to it. A principal design plus several related designs therefore covers a much wider area than a single registration.

The 2020 amendment: a 10-year window

In practice this means you can launch a product in Japan, see how the market responds, and then add the follow-up models you develop as related designs — as long as you stay within the 10-year window.

Limits you should know

Because of the second point, "we have 10 years" should not become a reason to wait. If you already plan variants, filing them before they are announced is the safest approach.

Partial design vs related design at a glance

The two systems can be combined: a partial design can itself serve as a principal design, with variations of that part filed as related designs.

Combination strategies that work in practice

• Whole design + partial design: the whole design covers full copies; the partial design covers products that reuse only your signature feature. Especially useful for products sold on e-commerce platforms, where look-alikes appear quickly.
• Principal design + related designs: file the base model as the principal design and known variants together; add later models within the 10-year window.
• One multiple-design application: since April 2021, up to 100 designs can be filed in a single application form. Whole, partial and related designs can go into one filing, which simplifies paperwork — but the JPO fee is still charged per design, and each design becomes a separate right.

Filing in Japan from abroad

Applicants without a domicile or business office in Japan must file through a Japanese patent attorney (Benrishi), and responses to refusals also go through the attorney. Some practical points for foreign applicants:

• Paris priority — 6 months: if you first filed in China, Korea, the US, the EU or elsewhere, you can claim priority in Japan within 6 months. Your home drawings may need adjustment to show partial designs the Japanese way (solid vs broken lines) — check this early.
• Hague designations: partial designs can also reach Japan through the Hague system, but Japan-specific requirements apply, and any refusal must be answered through a Japanese patent attorney.
• Already disclosed? Japan has a 1-year grace period for your own disclosures, but it must be claimed at filing and proof submitted within 30 days.

Official JPO fees

For example, one whole design, one partial design and two related designs mean four designs: JPY 64,000 in filing fees alone, plus annual fees for each registration. More designs mean broader protection but also higher maintenance costs, so focus on the features and models that matter commercially. Attorney fees vary by case — send us your drawings for a free quote.

FAQ

• Q. Can we file only a partial design?
  A. Yes. But to cover full copies as well, it is often wise to combine it with a whole-product design.
• Q. Our design is already registered in Japan. Can we add related designs now?
  A. Yes, within 10 years of the principal design's filing date and while the principal design right is in force — unless a similar third-party design has appeared in the meantime.
• Q. Can we sell only one related design to another company?
  A. No. Principal and related design rights cannot be transferred separately.
• Q. Can we use our Chinese drawings for a partial design in Japan?
  A. Often yes, with adjustments. We check how the claimed part is shown and adapt the drawings to Japanese practice before filing.
• Q. Can we communicate in English or Chinese?
  A. Yes. Every case is handled personally by a licensed Japanese patent attorney, and we communicate in English and Chinese. Payment by bank transfer or PayPal (JPY) is available.

Related articles

• How to File a Design Application in Japan: Process, Drawings and Timeline for Foreign Applicants
• How Much Does Design Registration Cost in Japan? Official JPO Fees for Foreign Applicants (2026)
• Protecting GUI, Icon, Building and Interior Designs in Japan: What Qualifies Since 2020
• Utility Model vs Patent in Japan: Which Should Foreign Applicants Choose?