This guide will be a brief and easy tutorial on extracting or modifying the in-game files. This serves mainly fan translation efforts, but you can do other things like replacing textures to give Parin a silly face, etc.

Falcom uses its own compression format, which we'll need to extract and repack. The main files are:

• itm
  - Basically the .zip file. These contain .txt files (dialogue and other code related to text), audio, and other images. This is the bulk of what you'll want to modify if you're doing a translation.
  
• itp
  - These contain sprites, textures, and other bitmaps. These are used in the PSP version.
  
• iti
  - Same as .itp. ,cf02 files are the images used for facial expressions if you want to modify those, like this guy did (cf02_00.iti is the default face). mp_0113, mp_0121, mp_0203, & mp_0209 contain the shop signs. mp_733 contains the DANGER sign in Motoro's gym. o_028 contains the textures for the signs you find in levels. char02b2 - the texture for the outfit in the Falcom intro cutscene, but not in-game char02bz - in-game outfit char02b1.iti head/hair
  
  
  
• it3
  - These contain 3d models. Use IT3 Converter (it3cnv) to extract these, and IT3 or CompileTools[github.com] to repack them (haven't tested).
  
• mmv
  - Custom Falcom format. These contains the image files used in transition text (credits, stage names, etc.). You don't need to touch these unless you want to go all the way in your fan translation, as these will require image editing and repacking into an .MMV file. You can convert them to GIF via https://gist.github.com/Kyuuhachi/e4c138c0f7913863feb70f175a505190#file-mmv-py, but there's no way to repack them currently. falcnvrt can also convert mmv to png, but it only works with the original JP Gurumin.
  
• vag
  - Sony's audio format, used in the PSP version for dialogue. You can convert to .wav using RCOMage. A DDL is included below.
  
• at3
  - Another Sony audio format, used in the PSP version (BGM).
  
• de2
  - Audio format. You can convert to .wav using vgmstream.

You can download the tools here:
https://github.com/Aureole-Suite
mediafire [dot] com/folder/3xd1misdnh92q/Gurumin
https://github.com/M-bot/CompileTools
https://www.pokanchan.jp/dokuwiki/software/falcnvrt/start (falcnvrt only works with the original JP Gurumin, since it targets the .arc files that come with the installation disc/zip).
https://www.pokanchan.jp/dokuwiki/software
https://github.com/kode54/vgmstream
http://www.psx-place.com/threads/research-rcomage-psdevwiki-mod.17958/

For this, we're going to be using itmcnv (ITM Converter). Gurumin stores its dialogue and text primarily in two types of files, with a few minor ones:

• map.itm (/bin)
  This contains the code that the game uses for speech bubbles, prompts, and so on. Dialogue, etc. is marked with MESSAGE, MES, & SELTEXT, but you can just Ctrl-F " to find most or all of the text. To extract itm files, drop it onto itmcnv.exe or use the batch. After modifying the text, drop it again to convert it back. Copy it into the appropriate folders and playtest.
  
  In the code, KaguTest2(10008, #) is used for non-conversational popups such as when you receive upgrades, how to do new moves, or when you examine misc. objects. In the following example, all of the lines would be loaded and crammed into one speech bubble.
  
  KaguTest2(10008,0,"Dad　took　all　these　photos.");
  KaguTest2(10008,1,"Scenery　from　around　the　world...");
  KaguTest2(10008,2,"Too　bad　they're　all　blurry.");
  
  For some reason, the game doesn't render half-width commas. Commas must be in full-width (“，”) to render.
  
  IDSP is an ideographic space used in Asian languages (“　”) in place of the regular half-width space. You might be able to remove these entirely without affecting the dialogue.
  
  
• various .itm files (/3dData)
  These contain the dialogue subtitles used in cutscenes as well as other bitmaps that have text on them (the in-game manual, the reaction speech bubbles, etc.). The dialogue is marked with ZIM before it.
  
• MicroMV (.mmv) files (/3ddata)
  These are image files used for any text that has transition effects (area names, boss cards, credits).
  
  
• Various .iti files (/3ddata)
  These contain textures with text on them. Note that the signs, etc. are usually in English in the Japanese version, so this is entirely optional. Use ITI Converter (iticnv) to extract and repack these.
  

• The Gurumin Wikia's modding [gurumin.wikia.com]section, for leading me to the tools posted here.
  
• M_Bot for helping me locate the iother n-game text (map.itm).