Episode 38

The *Palworld* lawsuit and related patent applications have been a topic of discussion.
This is a patent infringement lawsuit filed by Nintendo Co., Ltd. and The Pokémon Company against Pocketpair, Inc., the developer and distributor of the game software *Palworld*.
When it comes to rights infringement regarding game software, both copyright infringement and patent infringement are potential issues.
Copyright infringement lawsuits require proving both similarity and reliance, which sets a high hurdle. For instance, GREE, Inc. sued DeNA Co., Ltd. and others, claiming that the mobile internet game *Tsuri-ge Town 2* infringed on the plaintiff's copyright; while the court of first instance granted an injunction and partial damages, the appellate court found no copyright infringement and overturned the initial ruling.
In patent infringement lawsuits, the claim is typically that the game's algorithms infringe upon the plaintiff's patent rights. Plaintiffs can gain a strategic advantage by splitting off and continuing a portion of the original patent application, and subsequently filing a divisional application tailored to the allegedly infringing product.
Defendants can avoid infringement by altering the design of the accused product. In such cases, the plaintiff might argue the "doctrine of equivalents" or file a new divisional application aligned with the redesigned product.
Defendants may also raise a defense based on grounds for invalidation (Article 104-3 of the Patent Act).
Patent infringement litigation is akin to mixed martial arts. Even when you believe you are gaining the upper hand, a counter-move by the opponent can instantly turn the tables.
Courts often seek to resolve cases through settlement rather than a formal judgment (Article 89 of the Code of Civil Procedure). Settling the case allows the court to avoid the burden of drafting a judgment. While court records are generally open to the public (Article 91, Paragraph 1 of the Act), the portions concerning settlement terms are kept confidential (Article 91, Paragraph 2, Sentence 2), allowing the parties to avoid public disclosure of the settlement details.
In the *Palworld* lawsuit, a divisional application (Patent Application No. 2026-19762)—derived from the patent forming the basis of the claim (priority date of the original application: December 2021)—has drawn attention after receiving a notice of refusal citing a video of game software submitted via a third-party information submission. The cited video dates back to 2013.
It is presumed that the plaintiff filed the divisional application in hopes of securing more favorable settlement terms should the court recommend a settlement; however, by receiving a refusal based on a video published prior to the priority date of the original patent, they effectively provided the opposing party with grounds to argue for the patent's invalidity. In short, they stirred up a hornet's nest.

Episode 37

In this installment, I will explain partial designs and the determination of their similarity.
Traditionally, an "article" was defined as a tangible object circulating in the marketplace; parts of an article that could not be traded independently were not treated as "articles" under the Design Act, and designs pertaining to parts of an article were not eligible for protection.
However, there was an increase in "clever" imitations—where the overall design avoided infringement while incorporating a creative and distinctive part—making it impossible to adequately protect the investment involved. Consequently, the 1998 amendment expanded the scope of protection to include designs pertaining to parts of an article (*Commentary on Industrial Property Laws, Article by Article*).
Regarding the similarity of such partial designs, the courts have ruled as follows:
The partial design system aims to protect a registered partial design when the design of the specific part is identical or similar to that of another design, even if the overall shape of the article (indicated by broken lines) differs. Therefore, when determining the similarity of partial designs, one must ensure that differences in the position (or similar attributes) of the registered part versus the corresponding part do not defeat the purpose of the partial design system. Differences in position that can be interpreted as anticipated—such as changes in position within a reasonably conceivable range, viewed in light of the shape of the broken-line sections and the content of the partial design—do not affect the determination of similarity (IP High Court Judgment, January 31, 2007; Case No. 2006 (Gyo-Ke) 10317).
For cases involving similarity where the principal design is a "whole design" (design for the entire article) and the application for a related design is a "partial design," the IP High Court judgment of May 29, 2025 (Case No. 2024 (Gyo-Ke) 10108) serves as a useful reference. This lawsuit seeks the rescission of an appeal decision (Appeal No. 2023-19811) upholding a refusal of registration based on Article 3, Paragraph 1, Item 3 of the Design Act.
The design of the present application consists of a so-called flange portion—a part of the article (a packaging container)—whereas the cited design (the registered design at issue) encompasses the entire article (a storage container); thus, the two differ significantly in terms of "use, function, position, size, and scope," as well as shape. Consequently, the design of the present application cannot be considered similar to the cited design and is ineligible for registration as a related design under Article 10, Paragraph 1 of the Design Act.
Furthermore, since the design of the present application cannot be registered as a related design, the cited design (the registered design at issue) is not subject to the application of Article 10, Paragraph 2 of the Design Act; therefore, the cited design cannot be deemed not to fall under Article 3, Paragraph 1, Item 1 or 2 of the Act. The articles associated with the design of the present application and the cited design are a "packaging container" and a "storage container," respectively, sharing common uses and functions. Additionally, the relevant portions of both designs consist of a flange located on the left and right sides of the article, extending from the upper third of the outer edge to the top of the article; they share characteristic features—such as the shape of the flange's upper end, the appearance of the flange in a side view, and a pronounced indentation following a raised section at the flange's lower end—indicating a similarity in shape. Accordingly, the design of the present application is considered similar to the cited design (or the relevant portion thereof) and is ineligible for design registration pursuant to Article 3, Paragraph 1, Item 3 of the Act.
When comparing a "principal design" (which is a design for the whole article) with a "related design" that is a partial design, the comparison involves the entire principal design versus the specific part of the design for which registration is sought. In contrast, when comparing the design for which registration is sought with a cited design (a publicly known design), a lack of novelty (under Article 3, Paragraph 1, Items 1–3 of the Design Act) is recognized if even a portion of the cited design is identical or similar; thus, the comparison involves the design for which registration is sought versus a part (the cited portion) of the cited design. Consequently, when one design is a partial design and the other is a design for the whole article (whether a cited design or a principal design), the scope of comparison differs depending on whether one is determining the similarity between a principal design and a related design (which is a partial design) or determining the similarity (regarding novelty, etc.) between the design for which registration is sought and a cited design.
Based on the above, as a general rule, it is not permissible to register a design for the whole article as a principal design and a partial design thereof as a related design.
In the case of patents, the relationship between earlier and later applications is determined by comparing the inventions described in the respective claims; however, regarding novelty and similar requirements, the comparison is made between the invention described in the claims of the application in question and the entirety of the published earlier application (including its specification). A similar approach applies to designs.

Episode 36

This time, I will explain the concept of similarity in designs.
Design similarity arises in two contexts: the examination stage (Article 3, Paragraph 1, Item 3 of the Design Act) and the post-registration stage (Articles 23 and 24, Paragraph 2 of the same Act).
According to a Supreme Court judgment (Supreme Court Judgment, March 19, 1974, Third Petty Bench, Case No. 45 (Gyo-Tsu) of 1970; *Minshu* Vol. 28, No. 2, p. 308):
1. A design similar to a registered design (Article 23 of the Design Act) refers to a design that, when applied to an article identical or similar to the article associated with the registered design, evokes an aesthetic impression in general consumers similar to that of the registered design.
2. Based on the above, the similarity referred to in Article 3, Paragraph 1, Item 3 of the Design Act concerns the similarity of aesthetic impressions regarding the design of an article, viewed from the perspective of general consumers.
3. Article 3, Paragraph 2 of the Design Act removes the restriction regarding the identity or similarity of articles; instead, it focuses on the novelty or originality of the design's concept—viewed from the perspective of a person skilled in the art—based on motifs that are widely known in society.
In this Supreme Court judgment, the Court rejected the "creation by a person skilled in the art" theory regarding design similarity and adopted the "confusion by general consumers" theory.
However, it was pointed out that some court precedents and practices evaluated design similarity from the perspective of persons skilled in the art (such as designers). This coexistence of differing judgment methods—diverging from the Supreme Court precedent—led to a lack of clarity regarding how design similarity is determined (as noted in the explanatory materials for the 2006 amendment).
Consequently, Article 24, Paragraph 2 was added to the Design Act during the 2006 amendment, stipulating that "the determination of whether a registered design and another design are similar shall be made based on the aesthetic impression evoked through the visual perception of consumers." Taking into account the numerous court precedents that adopt the perspectives of traders and consumers when determining the similarity of designs, the law was stipulated to base such determinations on the presence or absence of a common aesthetic impression evoked in "consumers"—rather than "general consumers" (Commentary on Industrial Property Laws).
So, who exactly constitutes a "consumer"? The "Roof Tile Case" (Intellectual Property High Court Judgment, June 12, 2023; 2023 (Gyo-Ke) No. 10008) serves as a useful reference here. This lawsuit sought the rescission of a trial decision (Invalidation Trial No. 2021-880006) regarding the invalidation of a design registration under Article 48, Paragraph 1, Item 1 of the Design Act (on the grounds of violating Article 3, Paragraph 1, Item 3).
In that judgment, the court held: "While the determination of whether a registered design and another design are similar is based on the aesthetic impression evoked through the visual perception of consumers (Article 24, Paragraph 2 of the Design Act), the article pertaining to the design in question—roof tiles—involves not only the construction contractors who install them as consumers but also the clients (property owners) who order the roofing work and become the owners of the finished product; these clients are also significant consumers. Furthermore, even construction contractors must ultimately prioritize the aesthetic perspective of the client following installation. Therefore, the assessment of aesthetic impression—a key factor in determining similarity for the design in question—should be conducted from the perspective of the aesthetic values ​​prioritized by the client after installation, rather than solely from that of the construction contractor."
However, there is a logical leap in this lawsuit: the court based its similarity determination on Article 24, Paragraph 2 of the Design Act, even though the issue at hand concerned similarity under Article 3, Paragraph 1, Item 3. Ideally, the determination should have been grounded in Supreme Court precedent (Supreme Court Third Petty Bench Judgment, March 19, 1974; 1970 (Gyo-Tsu) No. 45; *Minshu* Vol. 28, No. 2, p. 308). When assessing similarity based on the aforementioned Supreme Court precedent—which focuses on "similarity of aesthetic appeal from the perspective of ordinary consumers"—the determination must be based on the aesthetic appeal as perceived by the client (the party ordering and ultimately owning the roof) rather than by the construction contractor performing the work. While the conclusion remains the same, the underlying reasoning differs.
On the other hand, in infringement litigation, similarity at the time of infringement is assessed based on Articles 23 and 24(2) of the Design Act. If a defense of invalidity is raised in such litigation, similarity at the time of the examination decision is assessed based on Article 3(1)(iii) of the Design Act. Although both assessments rely on "aesthetic similarity from the perspective of general consumers," this perception can change over time.
In recent years, the spread of social media and similar platforms has shown that the values ​​held by general consumers can shift rapidly. Consequently, a design might be deemed dissimilar at the time of infringement but similar at the time of the examination decision, or vice versa.
If, in future infringement litigation, a party can demonstrate that "aesthetic similarity from the perspective of general consumers" has changed over time, it is possible that court rulings will emerge where the determination of similarity differs between the time of infringement and the time of the examination decision.