MMD Tools Append is a companion addon, and it lives on two branches

It extends MMD Tools rather than standing on its own

MMD Tools Append is described as a Blender addon for adjusting scenes, models and materials in concert with MMD Tools, the separate addon maintained by the same organisation. The relationship matters more than the feature list here, because the two are designed to run side by side rather than one replacing the other.

The README states the purpose in two languages, English and Japanese, and the Japanese line is the same claim in a different wording rather than a separate scope. So the addon sits in the MMD workflow as an extension point: the base addon handles the MMD format, and this one adjusts what the base addon produces.

The project was renamed. It was formerly MMD UuuNyaa Tools, and the current name carries the relationship to MMD Tools explicitly, which matters for anyone following an old tutorial or an old issue thread and wondering why the addon in the video no longer has the name in the title.

The repository itself is small, and the shape of it is informative. The top level holds the addon package directory mmd_tools_append, a locales directory for translations, a DEVELOPER_GUIDE.md, and the licence file. There is no build system, no compiled artefact and no dependency manifest to speak of, which is the normal shape for a Blender addon that is distributed as source and installed through Blender's own addon system.

Two branches cover two eras of Blender, and picking the wrong one breaks

The version compatibility table is the most useful thing in the README, and it is short:

| Blender Version | MMD Tools Append Version | Branch | |-----------------|--------------------------|-------------| | Blender 4.2-5.2 | MMD Tools Append v4.x | main | | Blender 3.6 LTS | MMD Tools Append v1.x | blender-v3 |

So the main branch is the current line, versioned v4.x and covering Blender 4.2 through 5.2, while the blender-v3 branch holds the v1.x line for people still on Blender 3.6 LTS. The gap between v1.x and v4.x is not a small patch difference, and the addon numbering follows the Blender era it was written for rather than its own release history in any obvious semantic versioning sense.

The practical failure mode is straightforward. An addon that uses an API removed in a later Blender release will fail to register or will throw when a panel is opened, and a Blender addon that throws on import is often reported as an empty menu item rather than as an error message the user can act on.

That is why the branch column matters. If your Blender is 3.6 LTS, the main branch is not the development version of your install, it is a version written for a different Blender. The reverse also holds: on a current Blender you want the v4.x line, and the older branch will not gain the features that come with the newer API.

This dual-branch approach is a cost the project pays for a user base that straddles Blender's LTS boundary, and it is the kind of maintenance that quietly eats the time a small team would rather spend on features.

The installation instructions live in the wiki, in two languages

There is no install command in the repository, and that is by design rather than by omission. The installation and usage section points at the MMD Tools Append wiki for details, with a separate link to the Japanese version of the same wiki page, and a YouTube video titled How to use MMD Tools Append sits next to those links.

For an artist, that arrangement is reasonable: Blender addons are installed through Blender's own addon preferences, and the wiki is where the steps live, including whatever version-specific guidance an addon's install flow needs. What it costs is reproducibility. A reader of the repository alone cannot tell you the exact steps, so a new contributor reading only the README will not know how to load the addon for a first test, and a user who asks for help in the issue tracker will be pointed at the wiki as well.

The two-language coverage of the documentation is a small thing that matters in practice. The README itself is bilingual, and addon localization is listed as one of the contribution categories, with a locales directory in the tree to receive it. For a community spread across language groups, that is the difference between a wiki you can follow and one you need a translator for.

The channels for help are the issue tracker for problems and requests, and the MMD and Blender Discord server for everything quicker, including the asset and feature requests the project lists as wanted contributions.

Assets are the contribution stream, not just code

The contribution list is unusual for a Blender addon because most of the entries are not software. Requests cover features and assets, with material and lighting named as examples, and there are separate entries for document writing and translation, asset creation for lighting, materials and accessories, asset maintenance, software development and addon localization.

That tells you the project is partly a content project. An addon that offers lighting setups, materials and accessories is only as good as the assets it ships, and the maintainers are effectively running a library that volunteers contribute to. Asset maintenance is listed separately from asset creation for a reason: keeping a material working across Blender releases is recurring work, and it is the kind that goes stale quietly.

For a prospective contributor, the DEVELOPER_GUIDE.md is the place to start for code or translations, since the README points developers and translators there for project guidelines and detailed workflows. Everyone else gets the issue tracker and the Discord.

The practical takeaway for a user is that this addon improves when people add to it, which is a different maintenance model from a project where only the maintainer can ship a new material. If you need a specific lighting setup for a scene, the request path is a normal part of using it.

Ported features keep their original licences alongside the GPLv3 code

The credits section is where the legal picture gets interesting, because the addon mixes code of different origins and assets of a different kind altogether.

The rigid body physics to cloth physics feature is the work of the author of the Miku_Miku_Rig project, and it was ported with that author's permission. Porting with permission is the right way to do it, and the credit exists so downstream users know where the feature came from.

The leg IK maker in the MMD Humanoid Generator and Renamer was ported from MMD Tools Helper by Hogarth-MMD, which is GPLv3. Since the addon itself is GPLv3, that combination is compatible, which is why the port could be taken at all.

The third credit is different in kind. The lighting thumbnail images depict the character Hatsune Miku of Crypton Future Media, under the Piapro Character License. Those are images of a copyrighted character used as previews, and they sit under a character licence rather than the software licence. In practice that means the images are not covered by the GPLv3 grant and carry their own conditions, while the code is.

The addon as a whole is distributed under the GPLv3, which obliges redistribution to keep the licence and the source available. For an artist publishing renders or a commercial project, the split is what to keep in mind: the tool is copyleft, the thumbnail imagery is not, and the assets you create with it are your own affair.

The project, its assets and its documentation are run by a community, and the last release tag, v4.5.13, came on the same day as the last push to the repository on 2026-09-20, with v4.5.12 in July and v4.5.11 at the end of June.

Editorial conclusion

MMD Tools Append is worth adopting if you already work in MMD Tools and want an addon for scenes, models and materials that the main addon does not cover, and if you are on a current Blender release where the v4.x branch tracks the supported versions. It is the wrong tool if you are on Blender 3.6 and expect current features, since that line lives on the older v1.x branch, and it is not a standalone MMD tool, because it is designed to work in concert with MMD Tools. Verify first which branch matches your Blender version, read the wiki page for your language before installing, and check the licensing of the lighting thumbnails and the character assets if you plan to publish your work, since the code is GPLv3 while the character images sit under a separate character licence.

Frequently asked questions

Official sources

1. Issues
2. License: GPL-3.0
3. MMD-Blender/blender_mmd_tools_append on GitHub
4. README
5. Releases