The script supervisor for prose
A continuity checker for novels and book series
Film sets have staffed a continuity supervisor for a century, because a story at scale cannot live in one head. Novels have the same problem. Bunsho is the first tool built to solve it the same way.
What continuity errors actually look like
They are almost never dramatic. They are the small facts that drift while you are busy writing the story: the mistakes readers catch on their first pass because you have read the page forty times and see what you meant, not what is there.
Character drift
Arvind is twenty-seven in chapter 3, and twenty-two in the same winter, nine chapters later.
Knowledge leak
Mira references the letter on page 5. She doesn’t learn it exists until page 8.
World rule break
Teleportation requires a metal artifact, except in scene 34, where nobody is carrying one.
How Bunsho checks a manuscript
Bunsho compiles your manuscript into story state: who knows what, who is where, what is broken, what an object means. Every fact is pinned to the exact sentence that established it, and checks run against that state, not against a vague impression of your text. So a finding is never “this feels off.” It is: “Mira references the letter on page 5; she doesn’t learn of it until page 8. Here are both sentences.”
Checking is a deliberate act, not an ambient process. Three honest buttons: Check this chapter before you move on. Review changes to re-check only what you have touched since the last pass. Full review for the whole manuscript. Your typing is never watched and never metered. The script supervisor reads when you ask.
Your manuscript is local-first: it lives on your device, not in our database. When you run a check, only the pages being checked are sent for analysis, and they are never used to train models.
Why a bigger context window doesn’t fix this
Most AI writing tools re-read your manuscript through a context window and improvise. That architecture forgets: eye colors change, the dead walk, characters know things they were never told, and the tool cannot cite why it believes anything. Bunsho’s thesis is three words: state, not context. Structured, provenance-carrying story state is what makes findings checkable, citable, and worth trusting.
We hold the engine to that standard mechanically. It ships against a planted-error benchmark: a novella seeded with six continuity errors and three decoys designed to bait false alarms. The gate is all six caught, zero decoys flagged, reproducibly.
Continuity errors that break cause and effect have a common name: plot holes. And the same story state that catches errors after the fact also constrains Director Mode, so drafted scenes can’t introduce new ones.
Common questions
What is a continuity checker for fiction?
A continuity checker reads a manuscript and flags places where the story contradicts itself: a character whose age drifts between chapters, an object that appears somewhere it was never taken, a scene where someone acts on information they were never given. Film productions staff this role on every set. Bunsho does the same job for prose.
Do I have to fill in a story bible first?
No. Bunsho builds the story state by reading your manuscript. Characters, places, objects, relationships, and world rules are extracted from your prose, each fact pinned to the sentence that established it. The story bible writes itself, then works for you.
Does it check while I type?
No. Checking is deliberate. You run a check when you want one: a single chapter, everything that changed since your last review, or the full manuscript. Your writing itself is never metered and never interrupted.
Does it work for a whole book series?
Today Bunsho checks continuity within a manuscript. Cross-book series canon, carrying one story state across a whole series, is the headline of our roadmap, because series writers feel this pain most.
Write fearlessly. Check before you move on.
Bunsho is in private beta. Join the waitlist and be among the first writers to put a script supervisor on your manuscript.
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