Record a tutorial on unpacking a Masu character model.

I really like learning about idol modeling in Gakuen Idolmaster, so I decided to unpack it.

Unpacking Files#

Tools needed:

Gakuen-idolmaster-ab-decrypt: https://github.com/nijinekoyo/Gakuen-idolmaster-ab-decrypt?tab=readme-ov-file

AssetStudio: https://github.com/RazTools/Studio/releases/tag/v1.36.00

First, download the complete Gakuen Idolmaster main body in the emulator, and then copy the /data/data/com.bandainamcoent.idolmaster_gakuen/files/octo folder to the root directory of the unpacking tool.

The following operations assume that Python and Pip environments exist on the computer by default.

Right-click on the root directory, open in the terminal, and enter pip install -r requirements.txt to install the required dependencies for the tool.

After installation, enter python ./main.py to decrypt the assets.

After running, you can choose to enter python ./export_asset_bundle.py to export all assets. However, this time we will only extract character models, so we won't extract all files.

Extracting Models#

After that, go to output/asset_bundle and search for files starting with mdl_chr. These are all character models. Taking Kotohne Fujita's regular clothes as an example, the file name structure is as follows:

Character Model_Kotohne Fujita-Hair
Character Model_Kotohne Fujita-Body
Character Model_Kotohne Fujita-Face

As can be seen from the above, a character in Gakuen Idolmaster consists of three parts, with the face model being universal for all skins, and the hairstyle may vary in different skins.

Copy the mdl_chr_fktn-base-0000_face, mdl_chr_fktn-hair-0000_hair, and all files with the prefix mdl_chr_fktn-casl. These are all the model files for Kotohne Fujita's regular clothes. Create a new folder to store them.

Open AssestStudioGUI.exe, and in Options - Specify Unity version, enter the current Unity development version used by Gakuen Idolmaster, 2022.3.21f1, otherwise AssetStudio will not be able to recognize it correctly.

Then select File - Folder and import all the files from the folder. Select Export - All assets to export all the materials.

Assembling Models and Applying Materials#

The following operations are explained under the assumption that you have a basic understanding of Blender operations and are for reference only.

After importing all the .obj files, start applying materials.
Smart people like you must know how to connect materials, right? ((I'll briefly mention the handling of certain parts here.


hri_hhl is the gray highlight on the top of the head, but using hhl directly is incorrect. It should be overlaid on hir_def. The a channel of hirdef is the position of all highlights (including the gray position on the top of the head), but the highlights are white, so you need to merge them into gray by yourself. hircolalp is the texture of the hair. The part of the white light on the top of the head and the black light on the edge of the hair in the game is temporarily uncertain, it may be sdw, and I don't know if there is any connection. hirco is the headwear hairprop part. There are two types of materials in the headwear that need to be separated. One is the scattered hair on the edge of the hair, corresponding to hirco col alp, and the other is the small accessories on the hair, corresponding to hir col alp.
- Quoted from NGA user 38417185

I separated the zipper part and applied materials to it separately.

Same as above, I separated the eye part and applied materials to it separately.

Here is a reference for a finished .blend file. Please don't judge me too harshly.
https://www.123pan.com/s/gPN4Td-FNE8d.html Extraction code: fktn


After extracting the models, I don't know how to extract the skeleton. I hope someone can help me with this. ((

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