What does -dono mean in light novels?

You know -san and -sama, and then a knight in a fantasy novel calls the hero "Kazuki-dono" and the whole sentence sounds like it's wearing armor. The question of what -dono means comes up because the suffix is common in fiction and rare in life, and the gap between the two is where the flavor is.

What -dono means

-dono is a suffix of address that once ranked above -sama. It comes from a word for a lord's residence and by extension the lord, and in the warrior era it was how one samurai addressed another with respect but without submission. Today it survives on formal documents, in a few institutions, and in period fiction, where it's the sound of a sword at someone's hip. In modern speech it's nearly extinct, and a young Japanese reader meets it in historical dramas and fantasy novels before they ever hear it said.

What it means in the source culture

In a light novel, -dono tells you two things about the speaker. One is that they're formal in an old-fashioned, martial way: a knight, a soldier, a retainer, a character who speaks like a samurai whether or not the setting has any. The other is that they consider the person they're addressing an equal or a superior in a public, dignified sense, with none of the personal devotion -sama carries. A guild sends its letters with -dono. A general addresses a rival general with -dono. A servant does not use it, and neither does a friend.

It travels with a whole speech pattern. Characters who say -dono often also use archaic verb endings, refer to themselves with old pronouns, and end sentences with a formal flourish that Japanese readers associate with samurai in period drama. In a fantasy world with no Japan in it, that's a deliberate choice: the writer is dressing a character in a recognizable costume, and Japanese readers see the topknot even under a European helmet.

How translators handle it

Keep it. "Kazuki-dono" stays, and readers who know -san and -sama learn one more. It's exact and it preserves the oddity, which is part of the point, since the suffix is meant to sound a little archaic in Japanese too. The cost is one more untranslated thing on the page, and in a setting where the translation has otherwise turned -sama into "Lord," a stray -dono sticks out.

Use a title. "Sir Kazuki," "Lord Kazuki," "Master Kazuki." This reads naturally and fits the martial register; "Sir" in particular carries the respect-between-equals sense well. The trouble is that -dono attaches to people who hold no title, and "Sir" on a commoner who happens to be strong is a promotion the book didn't make.

Drop it and stiffen the sentence. The knight says "Kazuki" but speaks in full sentences with no contractions, so the formality lives in the syntax. This works when the character's whole manner is archaic anyway, and fails when the suffix was the only sign.

What we'd choose

Keep -dono when the book keeps its other suffixes, and turn it into "Sir" or "Lord" when the book has translated the rest, so that the reader never has to hold two systems at once. The contrast matters more than the suffix itself. If a knight calls everyone -dono and then calls one person -sama, or by their bare name, the book has said something about that person, and the translation needs a register for the knight's normal speech distinct enough that the exception shows.

Suppose a knight-captain addresses the summoned hero as "Kazuki-dono" through the first arc, correct and cool. After the hero saves her squad, she calls him "Kazuki." A translation that had been using "Sir Kazuki" can land that shift; one that had been using his bare name all along has nowhere to go.

How to read it comfortably

Hear -dono as a bow between equals. It's a soldier being polite to someone they'd fight beside, with no affection in it and no servitude. When it appears in a fantasy with no samurai in it, enjoy the costume, because the writer meant you to.

A translation that picks one way to render the suffix and keeps it for the whole book is one where the day the knight drops it still means something; you can read it in Crossleaf.