Writing Natural Japanese
Naturalness in writing should be judged from the context in which the text appears and the relationships of meaning it is intended to convey. Treating it as a matter of features such as particular vocabulary, syntax, punctuation, or sentence length only produces writing that sounds like it came from a different LLM.
Priorities
- Preserve facts, meaning, qualifications, causality, possibility, certainty, and domain-specific distinctions.
- Follow the terminology, orthography, style, and style exemplars specified by the user.
- When existing text is available, do not unnecessarily homogenize the writer’s vocabulary, tone, information density, use of symbols, or degree of informality.
- Respect expressions established for a particular purpose, audience, medium, or field.
- Clarify any point that would otherwise require readers to make extra inferences to reconstruct the relationships of meaning.
In the name of naturalness, do not weaken the meaning or add explanations that make claims more definite.
Establish the Context
Infer the purpose, audience, medium, field, and existing voice from the request and the input text.
You need to identify the natural Japanese persona suited to each situation, whether it is an academic paper, an email, or a casual chat with a close friend.
Identify the Invariants of Meaning
Before rewriting, confirm what must not change.
- Who is stating or doing what about which target
- What happened, what was done, or what state resulted
- Relationships of cause, condition, result, contrast, and exception
- Numbers, points in time, ranges, and preconditions
- Distinctions between technical terms or concepts
- Ambiguity that has been intentionally retained
Examine the Semantic Structure
What the Predicate Expresses
Check whether the action, state, or change represented by the predicate, and the objects involved, are clear to the reader.
In Japanese, subjects and objects are often naturally omitted, so do not supply them merely because they have been omitted. However, if there are multiple possible referents, the responsible party is important, or the target of an operation is unclear, reintroduce the necessary nouns.
The goal is not to explicitly state “who did what to whom, and how” in every sentence. The goal is to make it possible to reconstruct the necessary relationships naturally from the context.
Make Abstract Language Concrete
Do not reject terms such as “breaks,” “works,” “hits,” “crushes,” “silently,” “falls,” or “failure mode” merely because of the terms themselves. The problem is that such predicates are overly abstract and increase ambiguity.
For example, “When the cache expires, it breaks silently” does not make clear what fails or what “silently” means.
If the actual behavior is known, write at the level of observable states: “When the cache expires, it returns an empty result without raising an error.”
“This is the same failure mode as before” may be difficult to understand in an everyday conversation unless the details of the failure are shared. If it means that the same failure has occurred again, it can be written as “the same failure occurs as before.” Provide concrete details only when the content is known.
Conversely, preserve established technical terms and their distinctions, such as “failure mode” in reliability engineering.
Never replace an abstract expression with another abstract expression.
Expand Compressed Relationships Only as Needed
Check whether nominalization, nominal sentence endings, chains of nouns, slashes, or interpuncts conceal actions, causality, comparisons, or conditions.
If “consideration of an output-quality improvement policy” makes the relationships unclear in ordinary explanatory prose, it can be expanded to “consider how to improve output quality.”
On the other hand, preserve noun phrases as a medium when they are natural in headings, tables, notes, or similar formats.
Do not remove actions or causal relationships merely to shorten the text and force readers to infer them.
Check Referential Dependencies
If terms such as “this,” “that,” “both,” or “one” could refer to multiple objects, restate the necessary noun.
If the antecedent of a modifier is ambiguous, change the word order or split the sentence.
Preserve the Strength of Causal Relationships and Correlations
When translating or rewriting, do not turn causation into correlation, possibility into certainty, or suggestion into proof.
Rather than mapping words such as cause, drive, enable, allow, suggest, indicate, and silently one for one, reconstruct in Japanese the actual causal relationship, capacity, permission, and strength of inference expressed by the sentence.
Subject–Object Collocation
Check whether combinations of subjects, objects, and predicates are used naturally in the relevant field and context.
When correcting unnatural syntax or strong metaphors derived from English, do not change causality or certainty. See the contrast example of “subject-object collocation” as well.
Examine Roles Within the Text and Context
Check whether introductions, contrasts, emphasis, and connections actually express their relationship to the content that follows. If they merely preview or restate the content, they can be omitted.
Likewise, concession constructions, redefinitions, and rhetoric of betrayal do not always serve a meaningful role. A text does not necessarily need to contain oppositional structures or surprises. A structure that exists across the text as a whole does not necessarily hold on a sentence-by-sentence basis either.
In particular, when a sentence with a negative nuance exists only to make the surrounding text stand out, readers are likely to expend unnecessary attention on it.
Assess boldface, bullet points, parentheses, dashes, emoji, and nominal sentence endings by their contextual function rather than by their mere presence.
Vocabulary and Expertise
Prioritize terminology established within the relevant field.
For unnatural calques or collocations, do not mechanically replace a suspected source-language word with another word. Rewrite it based on the action and relationships that the sentence expresses.
When external sources are available, prioritize actual usage in textbooks, academic societies, government agencies, standards, and official documents over possibilities listed in dictionaries.
Avoid Overcorrection
Passive voice, inanimate subjects, nominalization, Sino-Japanese vocabulary, katakana words, metaphor, nominal sentence endings, connectives, and symbols need not be avoided in themselves. (This does not deny that unnatural Japanese often contains these elements.)
However, revise them when they obscure the subject, object, state change, causality, or qualifications and require readers to make unnecessary inferences.
Examples
Examples of unnatural Japanese that are especially likely to occur within a single sentence are presented in sentences.
Completion Criteria
- Facts, qualifications, causality, certainty, and domain-specific distinctions are preserved.
- Readers can reasonably reconstruct the necessary actions, targets, state changes, and conditions.
- No passages remain where an abstract expression has merely been replaced with another abstract expression.
- The text suits its purpose, audience, medium, and field.
- No changes have been made solely to bring the text closer to fixed writing conventions.
- No information or technical terminology absent from the source text has been introduced.