CST File

What are CST files and how to open them

Are you having problems opening a CST file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CST files.

What is a CST file?

CST files have multiple uses, and ComicStudio Story is one of them. Read more about the other uses further down the page.

ComicStudio Story

ComicStudio is a Japanese drawing program mainly used by illustrators, manga artists, and animation studios. It saves the story-line of a comic in files using file extension CST.

How to open CST files

We have identified two CST openers that are compatible with this specific type of CST file.

Programs that open ComicStudio Story files

Last updated: September 19, 2026

All known file formats using extension .CST

While ComicStudio Story is a popular type of CST-file, we know of 6 different uses of the .CST file extension. Different software may use files with the same extension for different types of data.

Banner Blue Movie Guide Library Auxiliary File

Banner Blue Movie Guide Library Auxiliary files store movie data used by the DOS program Banner Blue Movie Guide, a searchable database of films that includes built-in trivia games released in 1991. These auxiliary files contain additional data needed by the program to provide extended information, summaries or linked content around the movie entries in its main database.

These files are created and used only by the Banner Blue Movie Guide program. Records in the main database refer to these auxiliary files so that when the user browses or searches for information (for example descriptions, different versions, or supporting media), the program loads data from these auxiliary files alongside the main database entries to present a richer movie browsing experience.

These files were part of a collection of files with related extensions including NTS and SYN, and originally imported under the combined extension label CST/NTS/SYN. They are structured as text or binary data that Banner Blue reads and processes for searching and displaying additional movie metadata. The tool TRiD identifies these files by matching a specific byte signature at the beginning of the file.

Files begin with the ASCII signature "Banner Blue Movie Guide Library Auxiliary File. Version 1.0 … (C) Copyright 1991 Banner Blue Software Inc. - All Rights Reserved" followed by control bytes (including a 0x1A marker) at offset 0. This header string uniquely identifies the format and version.

While we have not verified the apps ourselves yet, our users have suggested ten different CST openers which you will find listed below.

CatSystem2 CatScene Script

CatSystem2 CatScene Script files serve as the scene scripting format used by the visual novel engine CatSystem2. They are produced by the engine's script compiler (mc.exe) and define the flow of scenes: displaying messages and speaker names, executing in-scene commands (such as background changes, sprite actions, sound or music playback), handling pauses and page breaks, and waiting for user input. These scripts are integral to defining how the story plays out in each scene.

The compiler generates this binary format from text-based scene script files. Once created, the engine reads the file at runtime to execute scene logic in sequence. Scene scripts are stored in compressed form (using zlib) within the file, and they are often bundled into larger archives (with extension .int) that group together many assets needed by the game. For localization work, tools exist that unpack the script into editable text (for messages, choices, names) and associated metadata (for commands and control flow), then recompile them back into the binary form to restore game behavior.

Files begin with an ASCII header identifying them as scene scripts, followed by compressed script data. Specifically, the first eight bytes of the file are "CatScene" in ASCII. That is followed by two 32-bit little-endian integers: the size of the compressed script chunk and its uncompressed size. After decompression, the script region includes a header of its own (with fields such as the script length, a table of input offsets, offset to the string offset table, and offset to the string table), followed by indexed entries each with a type (for example message, command, name, page break, or input) and associated content.

Director Cast Data

Director Cast Data files hold external cast libraries created by Adobe Director. These external cast files keep media assets - such as images, sounds, scripts or movies - separate from the main Director movie. They are created inside Director when the author saves or links a cast as external rather than embedding it inside the movie. This enables reuse of the same cast across multiple Director movies without duplicating the content.

In Director workflows the internal cast members are embedded directly in the .dir movie file. External casts reside as .CST files on disk. To use an external cast, Director links it into the main movie; then the cast's members can be used in the Cast window and dragged into the Score or placed on the Stage exactly as if they were part of the movie itself. Distributing movies built with external casts requires including those .CST files so that the movie can locate and load its cast members correctly.

These files use the same low-level container structure as unprotected Director cast files (the RIFX‐based RIFF format in big‐endian order). They include named data chunks such as memory maps, cast member mappings, asset references, and identifiers. The file starts with the ASCII signature "XFIR" at byte offset 0, contains tags like "ASSETS", "CAST", "THUMB", "MAIN", "PAMM" and "TSAC", and also includes the string "59CMPAMI" at offset 8. These internal signs help detection and differentiation from other formats using the same extension.

Manga Studio Story

Manga Studio Story files save the full structure of a multi‐page comic or manga project created in Manga Studio (also known as ComicStudio). They store page layouts, chapter and story information, panel arrangements, speech bubble placements, and references to the individual page artwork so that all pages in a story are managed as a single project.

These files are produced by Manga Studio (later replaced by Clip Studio Paint) when working in its "story" mode. A story project typically consists of multiple pages saved separately (using .CPG files) under chapter or page links. Manga Studio writes the .CST file; users open or import it in Manga Studio or in Clip Studio Paint (EX version) to convert it into a modern project format or to continue editing the story.

Internally, the file is a binary proprietary container with little public documentation. It tracks multiple pages (via .CPG files), layers, vectors, bitmap art, and chapter metadata. It begins with a signature of the ASCII string "TSSC" at the very start of the file and includes internal identifiers such as "PAGE0001" reflecting page numbering.

SMS Coastline data

SMS Coastline data files store one or more coastline lines used in the Surface-water Modeling System (SMS) software developed by Aquaveo. These are simple text files that define geographic shape boundaries for hydrodynamic or coastal modeling. Their main purpose is to supply SMS with coastline arcs (open or closed polylines) so that coastal features and ocean boundaries can be built in map modules, meshed, or used by models such as ADCIRC.

SMS writes coastline data when the user exports or saves coastline definitions, often after digitizing or importing them. Such files are read back into SMS via the File → Open command or Save As from the Map module. If a coastline is closed in the file, SMS treats it as an island. If no elevation (z-value) is supplied for each coastline node, SMS assigns a default z of 0.0. Each coastline is composed of straight line segments (nodes) defined by x, y (and optionally z) coordinates in sequence.

Typical structure begins with a file identifier line, followed by the number of coastlines. For each coastline: a count of segments and a flag (0 or 1) indicating whether it closes. Then each line supplies one node's coordinates (x, y, and optional z), one node per line. The final coastline has its own count and node list. All coastlines follow in order until end-of-file. The file starts with ASCII "COAST" at offset zero as signature.

Various apps that use files with this extension

These apps are known to open certain types of CST files. Remember, different programs may use CST files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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