The Japanese patent system is known for its rigor — but that rigor is not the product of bureaucracy. It reflects decades of precise consensus built between JPO examiners and patent attorneys (弁理士, benrishi). Behind every mandatory rule lies a legal rationale; behind every format requirement lies a real procedural need. For international practitioners, understanding why these rules exist matters more than simply memorizing what they are.

This guide begins with the document structure of a JP application and works through: specification organization, mandatory paragraph numbering, the マルチマルチクレーム prohibition, claim drafting conventions, abstract (要約書) requirements, and Japan-specific examination procedures. It closes with a systematic summary of the key differences between Chinese and Japanese practice. Whether you are localizing a CN draft into JP or handling a Japanese client's first application, this guide serves as a practical reference.

I. Structure of a Japanese Patent Application

Required Documents and Their Legal Basis

A non-provisional (非仮出願) application submitted to JPO requires the following documents:

Document (Japanese)	English Name	Required	Legal Basis
願書	Request (application form)	Required	JPO Form No. 26
明細書	Specification	Required	JPO Form No. 29
特許請求の範囲	Claims	Required	JPO Form No. 30
図面	Drawings	Optional (required when necessary to understand the invention)	JPO Form No. 30
要約書	Abstract	Required	JPO Form No. 31

It is worth noting that the Japanese 願書 is equivalent to a Chinese "request + power of attorney" combined in one document — in most cases, foreign applicants filing through a local agent do not need to separately submit a power of attorney. The invention title (【発明の名称】) appears both on the first line of the 明細書 and in the 願書 and must be identical in both locations.

Typical Benrishi Drafting Sequence

Japanese benrishi adopt a "top-down" claims-first approach:

特許請求の範囲 (Claims) — Establish the scope of protection first
明細書 (Specification) — Work backwards to build supporting disclosure and add embodiments
図面 (Drawings) — Assign reference numbers in coordination with embodiments
要約書 (Abstract) — Drafted last; includes the 選択図 (representative drawing)
願書 (Application form) — Fill in applicant, inventors, and agent information

This sequence is broadly similar to Chinese practice, but Japan places greater emphasis on finalizing the claims before expanding the specification — because every embodiment in the specification must provide textual support for the claims, and drafting in reverse order creates serious risk.

II. Specification Structure: Strict Section Order and Full-Width Brackets

Statutory Section Order

The section order in a Japanese 明細書 is strictly prescribed by JPO Form No. 29 and cannot be rearranged:

【書類名】明細書
【発明の名称】…

【技術分野】
【0001】…

【背景技術】
【0002】…

【先行技術文献】
  【特許文献】
    【特許文献１】特開2020-XXXXXX号
  【非特許文献】
    【非特許文献１】…

【発明の概要】
  【発明が解決しようとする課題】
  【課題を解決するための手段】
  【発明の効果】

【図面の簡単な説明】
【発明を実施するための形態】
【実施例】(optional for chemistry/pharma)
【符号の説明】

Key pitfall: section headings must match the JPO-prescribed wording exactly, wrapped in full-width brackets 【】. Using 「課題」 in place of 「発明が解決しようとする課題」, or writing 「形態」 without 「発明を実施するための」, will trigger a formality rejection. This is the most common mistake made by Chinese practitioners.

Comparison with Chinese Specification Structure

Item	China (CNIPA)	Japan (JPO)
Section labels	"Technical Field", "Background Art", "Summary of Invention"	【技術分野】【背景技術】【発明の概要】 (full-width 【】)
Paragraph numbering	Not mandatory (recommended in recent years)	Mandatory 【0001】 format
Section order	Relatively flexible	Strict per JPO Form No. 29
"Summary of Invention"	Single chapter	Split into three sub-sections: 【課題】【手段】【効果】
Independent claims	Must recite "essential technical features"	No such mandatory requirement; broad scope is permissible
Prior art documents	Embedded in Background section	Separate section: 【先行技術文献】
Abstract length	500 Chinese characters is common	Hard limit: 400 characters

III. Paragraph Numbers 【0001】: Immovable Anchors for Amendment

The Mandatory Rule Explained

In a Japanese 明細書, every body paragraph must begin with a four-digit number in full-width brackets: 【0001】, 【0002】 … When the count exceeds 9999, five-digit numbers are used: 【10000】.

This requirement derives from Japanese Patent Act Article 17-2, which governs amendments and prohibits the addition of new matter (新規事項追加禁止). The precise anchor for any amendment is the paragraph number — that is how examiners identify exactly which paragraph is being modified. If paragraph numbers are rearranged after filing, every cross-reference in subsequent amendment submissions becomes misaligned, causing serious procedural problems.

Which paragraphs get numbers, and which do not:

Numbered: each body paragraph of the specification text
Not numbered: section headings (e.g., 【技術分野】 itself)
Not numbered: special labels (【図１】【表１】【化１】【非特許文献１】, etc.)
Not numbered: figure captions in the drawings

【技術分野】          ← No number (section heading)
【0001】             ← First body paragraph
本発明は、〜に関する。

【背景技術】          ← No number (section heading)
【0002】             ← Body paragraphs continue in sequence
従来、〜であった。

Practical Meaning of Amendment Anchoring

Japanese Patent Act Article 17-2, Paragraph 3: "An amendment must be made within the scope of matters described in the specification, claims, or drawings originally attached to the request."

This provision means that once filed, the specification becomes a fixed reference baseline. When amending paragraph 【0015】, the JPO examiner will directly compare the amendment against the original 【0015】. If paragraph numbers have been reshuffled and the original 【0015】 has become 【0016】, the entire amendment reference chain breaks.

This is why experienced benrishi have deep professional aversion to "any tool that silently renumbers paragraphs" — such behavior is fatal in practice.

IV. マルチマルチクレーム禁止: The Most Important New Rule Since 2022

Definition and Violation Criteria

Effective April 1, 2022, under Japanese Patent Act Article 36, Paragraph 6, Item 4, and Ordinance for Enforcement of the Patent Act Article 24-3, Japan prohibits "multiply-dependent claims referencing other multiply-dependent claims" — that is, a dependent claim that already references multiple claims in the alternative (using "or") cannot itself be referenced by another multi-dependent claim.

The following illustrates what is permissible and what is not:

【請求項１】…装置。                            ← Independent (permissible)
【請求項２】…装置。                            ← Independent (permissible)
【請求項３】請求項１又は請求項２に記載の装置であって…  ← Multi-dependent (permissible)
【請求項４】請求項３に記載の装置であって…        ← Single-dependent on a multi-dependent (permissible)
【請求項５】請求項３又は請求項４に記載の装置であって…  ← Multi-dependent referencing a multi-dependent → マルチマルチ → PROHIBITED

Consequences Are Severe

A violation of the マルチマルチ prohibition does not merely result in that one claim being rejected. More seriously: the violating claim and all subsequent claims that reference it will not undergo substantive examination — no novelty, inventive step, or unity examination. This means an entire chain of claims can be barred from substantive examination before it even begins.

JPO has published a "multi-multi claim detection tool" and expects applicants to voluntarily amend before requesting examination.

Adapting a CN Draft to JP

When localizing a Chinese draft for JP filing, this is the most critical step to check. Both Chinese and US practice allow multi-multi dependencies, so directly reusing CN claim structure in JP will invariably produce violations.

Two adaptation strategies are common:

Splitting: break the violating multi-dependent claim into multiple single-dependent claims
Restructuring: a benrishi redesigns the entire claim tree, optimizing reference economy while preserving the scope of protection

V. Claim Drafting Style: Transitional Phrases and Format Conventions

Standard Format Example

【特許請求の範囲】
【請求項１】
  Aを備え、
  Bを有し、
  Cを特徴とする
  X装置。

【請求項２】
  請求項１に記載のX装置であって、
  Dをさらに備える
  X装置。

Each claim is preceded by its 【請求項N】 full-width bracket label; elements are separated by 「、」(Japanese comma); each claim ends with 「。」(full-width period). The referencing phrase for dependent claims is 「請求項Nに記載の〜であって」.

Choosing the Transitional Phrase

Japanese Phrase	English Equivalent	Usage
〜を備える	comprising	Open-ended; widely used in modern corporate applications
〜を特徴とする	characterized in that	Most traditional; used in most textbook examples
〜を含む	comprising / including	Common in chemistry and method claims
〜からなる	consisting of	Closed-ended; used to distinguish from prior art
〜を主成分とする	mainly composed of	Semi-open; used for chemical/material applications

Practical preference: large companies and applications that will be pursued in parallel in the US tend to use 「〜を備える」 (easily maps to "comprising"); traditional firms and chemistry/pharma applications often use 「〜を特徴とする」; 「〜からなる」 is reserved for situations requiring closed-form limitation to distinguish prior art.

Japanese-Specific Expressions

Method claims use 「〜する工程」 (step). Claim subjects can be one of five categories: 装置 (device), システム (system), 方法 (method), プログラム (program), or 記録媒体 (storage medium). Previously introduced elements are referenced using 「前記」 (equivalent to "said" in English). "At least one" is expressed as 「少なくとも一つの〜」.

VI. 要約書 (Abstract): 400-Character Hard Limit and Structured Format

Character Count and Structure Requirements

The Japanese 要約書 has a strict upper limit — within 400 characters (counted in Japanese characters), with 200–400 characters recommended. Abstracts of 500 Chinese characters are common in Chinese practice; reusing them directly will always exceed the Japanese limit.

The standard format is:

【書類名】要約書
【要約】
【課題】〜を提供すること。
【解決手段】〜を〜する構成とし、〜することにより〜する。
【選択図】図１

【課題】: A single sentence corresponding to 「発明が解決しようとする課題」 in the specification
【解決手段】: The core technical solution, corresponding to 「課題を解決するための手段」
【効果】 (optional): Included when there is a notable effect to describe
【選択図】: Designates the one drawing that best represents the characteristic features of the invention

The register is colloquial (〜する、〜である); classical forms (〜なり、〜せり) are not used. Expressions like "refer to the specification" are prohibited.

Rules for Selecting the 選択図

JPO Form No. 31 specifies that the 要約書 must designate a 「選択図」 — the single drawing among all figures that "best represents the characteristic features of the invention."

Selection principle: typically the overall system diagram or a cross-section of the core device. Only one figure may be selected. Reference numbers mentioned in the abstract body must be identifiable in the selected figure — which means drafting the abstract requires cross-checking against the drawing reference number map.

VII. Japan-Specific Procedures: Examination Requests, Accelerated Examination, and Utility Models

出願審査請求: The 3-Year Deadline You Cannot Miss

Japan operates a "deferred examination" system: after filing, an application does not automatically enter the examination queue. The applicant (or any third party) must submit a request for examination within 3 years of the filing date — failing to do so is deemed a withdrawal.

This differs fundamentally from China, where the examination request is submitted together with the application. In Japan, the examination request is a separate subsequent procedure with its own fee. The 3-year deadline is absolute; there is no extension mechanism.

Early Examination and Super-Early Examination

JPO offers three examination speed tiers:

Program	Average Time to First Office Action	Eligibility Criteria
Standard examination	10–14 months	—
Early examination (早期審査)	Approx. 2.7 months	SMEs, individuals, universities, applicants with implementation plans, applicants with a corresponding foreign application, etc.
Super-early examination (スーパー早期審査)	Approx. 0.8 months	Both "implementation-related" and "has a corresponding foreign application" must be satisfied simultaneously

Early examination is free of charge; it only requires submitting a "Statement of Circumstances Relating to Early Examination" (早期審査に関する事情説明書). For applicants who have already filed in the US or China and wish to obtain a JP grant quickly, the super-early examination is an exceptionally valuable acceleration path.

実用新案 vs. 特許: When to Choose Which

Comparison	特許 (Patent)	実用新案 (Utility Model)
Subject matter	Inventions (including methods and substances)	Only shape, structure, or combination of articles
Examination	Substantive examination	Formality examination only; no substantive examination
Time to registration	Typically 1–3 years	Approx. 2–6 months
Protection term	20 years	10 years
Enforcement	Direct enforcement	Must first obtain a 実用新案技術評価書 before enforcement
Suitable for	Substantial technical breakthroughs	Incremental improvements; short product lifecycle

The trade-off for fast utility model registration is a 10-year protection term and the extra step of obtaining a Technical Evaluation Report before enforcement. For startups with short product iteration cycles who want to establish patent protection quickly, the 実用新案 is a rational choice.

Prior Art Document Disclosure Obligation

Japanese Patent Act Article 36, Paragraph 4, Item 2: if, at the time of filing, the applicant is aware of prior art documents related to the invention, they are obligated to disclose them in the 【先行技術文献】 section of the specification.

This differs fundamentally from the US IDS system: the US IDS is a standalone disclosure statement; Japanese disclosure is embedded within the specification itself, with no separate form. The consequences also differ — failure to disclose in the US IDS can render the patent unenforceable; in Japan, non-disclosure results at most in a request to amend, and can be remedied through an amendment.

VIII. 新規事項追加禁止: Why the Initial Draft Must Be Written "as Thick as Possible"

The Core Rule

Japanese Patent Act Article 17-2, Paragraph 3 (Prohibition on Adding New Matter): all amendments filed after submission must stay within the scope of technical matters derivable from the matters described in the originally filed specification, claims, and drawings.

This rule has a fundamental impact on drafting strategy: because the amendment window is extremely narrow, any information that cannot be added later must be included in the specification from the outset.

Practical Drafting Strategies

Based on the new matter prohibition, Japanese benrishi typically adopt the following practices at the drafting stage:

Exhaust numerical range endpoints: when writing "10–20," the specification must also include specific intermediate values (e.g., "11, 12, 15, 19") in the embodiments, so that later amendments can narrow the range to any of those values
Genus concept + multiple intermediate sub-concepts + multiple specific embodiments: each level must appear explicitly in the original specification
Record all effects in the 明細書: effects not recorded in the specification cannot be asserted during prosecution — this is a major departure from US practice
Comprehensive coverage of variations (変形例): these serve as a reservoir of material for fallback amendments

This is also why Japanese specifications tend to be longer than their Chinese or European counterparts for equivalent inventions — not out of redundancy, but to preserve space for future amendments.

IX. Key Differences Between Chinese and Japanese Practice: Ten Pitfalls Every Practitioner Must Know

Chinese Practice	Consequence in Japan	Correct Japanese Practice
Section heading in Chinese (e.g., "Technical Field")	Formality rejection	Use full-width 【技術分野】
Paragraphs without numbers	Cannot precisely anchor amendments; unusable in practice	Mandatory consecutive 【0001】 numbering
Effects written in the claims	Noncompliant with JP specification standards	Effects go in 【発明の効果】 section
Independent claim must recite "essential technical features"	Unnecessarily narrows scope	JP has no such mandatory requirement; broad scope is permissible
Prior art references embedded in background text	Noncompliant with format	Separate 【先行技術文献】 section required
Transitional phrase "包括" (Chinese "including")	Language error	Use 「〜を備える」 or 「〜を特徴とする」
Abstract of 500 characters	Exceeds 400-character hard limit	Compress to within 400 characters
Claim numbers in half-width digits	Noncompliant with JPO format conventions	Full-width 【請求項１】
Missing reference number glossary	Incomplete specification structure	Add 【符号の説明】 at end of specification
Multi-dependent claim referencing another multi-dependent	That claim and all subsequent claims receive no substantive examination	Detect マルチマルチ and restructure

Pre-Submission Checklist: Required Verifications for a JP Patent Application

Before submitting a JP patent application, verify each item on this checklist:

Format Compliance

Full-width 【】 section labels; section names exactly match JPO Form No. 29
明細書 section order strictly follows Form No. 29 (技術分野 → 背景技術 → 先行技術文献 → 課題 → 手段 → 効果 → 図面説明 → 実施形態 → 符号説明)
Paragraph numbers 【0001】 consecutive and mandatory; no backfilling or renumbering
Claims use full-width 【請求項１】 bracket labels

Claims

マルチマルチクレーム check: no multi-dependent claim references another multi-dependent claim
Transitional phrase correct (choose one: 〜を備える / 〜を特徴とする / 〜からなる; do not mix)
Dependent claim 「前記」 references are consistent

Specification Content

【先行技術文献】 is a separate section subdivided into 【特許文献】 and 【非特許文献】
【符号の説明】 appears at the end of the specification; format is number … component name
All effects have been recorded in 【発明の効果】 (effects not recorded cannot be asserted later)
Numerical ranges have intermediate values or endpoint support recorded (prevents amendments from exceeding original scope)

要約書

Character count ≤ 400 (Japanese characters)
Contains the 【課題】【解決手段】 structure
【選択図】 designates the correct figure number

Procedural Matters

Determine whether to request early examination (strongly recommended when a corresponding foreign application exists)
3-year examination request deadline recorded in project management system
Applicant category confirmed (SMEs and individuals may qualify for 50% fee reduction)

Japanese patent practice is precise to a degree that makes many international practitioners uncomfortable at first encounter. But viewed from another angle, it is precisely this highly standardized format system that has enabled JPO to achieve examination efficiency and grant quality that ranks among the highest of any patent office in the world. Once these rules are mastered, Japan becomes a reliable and high-value node in any international patent portfolio.

Complete Guide to Japanese Patent Practice: Paragraph Numbers 【0001】, the Multi-Multi Claim Ban, and the Benrishi Workflow