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arc_unpacker - the visual novel extractor

arc_unpacker is a command line tool for extracting images, sounds, music and miscellaneous resources from visual novels (and some other Japanese games).


Drag and drop the archive or file onto arc_unpacker. It will guess the format and unpack it for you.


  1. The file format might be detected by two or more decoders at once. In such cases you need to tell the program which one to use by supplying --dec=... option.

  2. The file might need more parameters to be correctly unpacked. In such cases you need to supply them manually. For example, XP3 archives need --plugin that tells what kind of decryption to use. To tell it to use Fate/Stay Night decryption, supply --dec=krkr/xp3 --plugin=fsn.

To learn what parameter your game needs, you can either use --help to see all available parameters, or refer to your game details in the game list that lists all required parameters for every supported game.

To learn how to pass parameters to arc_unpacker, refer to this question.


  • I drag the game files onto arc_unpacker and it immediately closes.

    Try running it from the command prompt to see the output and possible error message. Usually this behavior is a sign that the game requires additional parameters which are described in the game list, or it's not supported.

  • What is command prompt?

    On Windows, it's cmd.exe. On Linux, I think you already know the answer to this question.

  • How do I pass additional options / parameters?

    (for Windows users)

    1. Open up cmd.exe and navigate to the directory where you downloaded arc_unpacker.exe by typing a command that looks like this:

       cd "C:\downloads"

      Alternatively, navigate to the arc_unpacker directory in Explorer, hold Shift and click with right mouse button anywhere, and select "Open command window here".

    2. To run arc_unpacker with your game without extra parameters, type a command that looks like this:

       arc_unpacker "C:\games\your game\file you want to unpack.dat"


       arc_unpacker "C:\games\your game\directory you want to unpack"

      Alternatively, type arc_unpacker (without hitting Enter) and drop a file onto command prompt. It should enter the path like above, saving you the effort of typing it manually.

    3. To pass additional parameters such as --dec etc., run arc_unpacker like this:

       arc_unpacker "C:\games\Touhou 08\th08.dat" --dec=team-shanghai-alice/pbgz

      To get list of possible parameters, see arc_unpacker --help. If your game needs any extra parameters, they're also outlined inside the game list.

  • Why command line? Why no windows / GUI?

    It'd take a lot of effort to make GUI for arc_unpacker:

    • cross platform - I'd need to use Qt or Gtk, and this adds to the project complexity (consider how we support five different compilers).
    • design - it's difficult to make a GUI that caters to most of use cases (recursive unpacking, selecting decoder, passing game key etc.)
    • effort - implementing it easily scales to dozens, if not hundreds of man hours. I'd rather focus on supporting more games.

    That being said, it's not entirely impossible for this to happen in the future. Once C++17 comes out, I plan to ditch some of the non-conforming compilers, which should ease things up a bit.

  • What do I do with .wavloop files?

    These files are audio loops. You can play them like normal .wav, however, most of the players will ignore looping information that is contained in such files. If you're looking for players that do support looped .wavs, I recommend either vgmstream, foo_input_wave_loop or wavosaur. The extension .wavloop was chosen so that it stands out from normal .wavs and for compatibility with foo_input_wave_loop.

  • I get std::bad_alloc, what gives?

    One option is that an archive contains a very large file, which causes arc_unpacker to run out of RAM while it tries to decode that file. To circumvent this (short of buying more memory), you can try running arc_unpacker with -t=1 --no-recurse which should reduce its memory footprint. Since there only were a few such archives spotted, no special mechanism was developed to work around this issue, although this might change in the future. Other options include corrupt game files or a specific kind of bug in arc_unpacker's decoders, but both are unlikely. If you are unable to unpack the files, do not hesitate to report the issue to the issue tracker.

  • How can I help with development?

    Thanks for asking this! There are a number of ways you can help:

    • By documenting games that are already supported but are not present on the games list.
    • By porting existing decoders from other projects. Example projects can be found in
    • By reverse engineering games that are not yet supported, and coding new decoders for them.

    For details, check out

  • Packing / encoding support?

    Not going to happen. Compiling files for games, especially from fan translation standpoint, almost always needs rolling your own script compiler, modifying the game .exe, fixing weird quirks, etc. - many things that wouldn't make sense for arc_unpacker to support. At the same time, the user base that might find encoders useful would be extremely small, and writing encoders is often much more difficult than writing decoders, so it's not very practical.