About Mojikumi and Yakumono in Japanese layout

Japanese typography requires precise control over character spacing to achieve professional results. Mojikumi defines spacing rules for different character types, while Yakumono controls how punctuation behaves within those rules.

Western typography uses kerning and tracking for letter spacing. Mojikumi serves a similar purpose for Japanese text, but with greater complexity. Unlike Western text, which primarily focuses on letter spacing, Japanese text must account for ideographic characters, roman characters, and punctuation relationships. These rules are essential for publications combining Japanese and Western texts.

Mojikumi spacing controls

Mojikumi controls how different character types space throughout your text. The system follows JIS X 4051:1995, the Japanese Industrial Standard for spacing conventions.

• Character relationships determine spacing between Japanese characters, roman characters, numbers, and punctuation marks.
• Line boundaries control line-start and line-end characters, defining which characters can appear at the beginning or end of lines.
• Paragraph structure manages indentation and overall composition of the paragraph.
• Justification behavior defines spacing adjustment, controlling how spacing changes when text fills a line.

InDesign includes predefined Mojikumi sets that implement common professional standards. You can select these presets from the Mojikumi menu in the Paragraph panel or create custom sets when your project requires specific spacing rules.

For Chinese text, the Mojikumi settings for Traditional Chinese and Simplified Chinese provide culturally appropriate spacing conventions. Korean text typically doesn't require Mojikumi, as Hangul characters follow different compositional rules.

Yakumono classification

Yakumono refers to punctuation marks and special characters in Japanese typography. These characters divide into three primary categories based on their spacing behavior:

• Okoshi yakumono (opening punctuation) includes opening parentheses, brackets, and quotation marks. These characters typically appear with reduced spacing before them to maintain visual balance.
• Uke yakumono (closing punctuation) includes closing parentheses, brackets, periods, and commas. These characters can compress the space after them, allowing the next character to position closer.
• 中点類 (Nakatenrui) (middle punctuation) includes middle dots (nakaguro), colons, and other marks that appear between words or phrases. These marks maintain consistent spacing on both sides.

The classification determines how characters behave during line justification and when kinsoku rules prevent line breaks at certain positions. For example, Kuten (Japanese period) (。) classified as uke yakumono can compress to allow text to fill a line without excessive spacing.

Spacing values

Each Mojikumi setting defines three values for character spacing: Desired, Minimum, and Maximum. These values provide flexibility during composition.

• Desired value represents optimal spacing under normal conditions. InDesign applies this spacing when composing text without justification or kinsoku processing.
• Minimum value defines how much spacing can be compressed when the composer needs to fit more text on a line. This compression occurs during kinsoku processing, when characters that cannot end a line need to move forward.
• Maximum value defines the maximum amount of spacing that can expand during full justification. When text must fill the entire line width, InDesign increases spacing up to this maximum across the line.

You specify these values as percentages of character width or in bu units (bu refers to a fractional unit of the Zenkaku (1 em). It represents values obtained by dividing the Zenkaku into smaller parts. For example, 4 bu equals 1/4 em, and 2 bu equals 1/2 em.
A value such as 2 bu 4 bu combines these fractions to produce 3/4 em). You can observe this behavior as you type. The larger the difference between Minimum and Maximum values, the more flexibility InDesign has to adjust spacing while maintaining even text color.

Mojikumi and text composition

Mojikumi settings interact with the InDesign composition engine to determine line breaks. When using Adobe Japanese Paragraph Composer, the system evaluates potential break points across the entire paragraph, weighing spacing quality against other factors such as Kinsoku violations.

The composer assigns penalties to different spacing scenarios. Spacing that deviates significantly from the desired value receives higher penalties. It then selects the combination of line breaks that minimizes the total penalty across the paragraph, producing the most even appearance.

This evaluation happens dynamically as you edit text. When you add or remove characters, the composer adjusts spacing on earlier lines to improve the overall result. As you type, you may notice text reflow on preceding lines as the paragraph is refined.

Use Mojikumi to control text composition and fix spacing issues. InDesign includes presets for common needs. Create custom sets for specialized fonts or unique project requirements.