Getting Started

This guide aims to help you get started modding 3DS Yo-kai Watch games.

Dumping RomFS and Extracting Main Archives

Dumping RomFS

First you will need to Dump RomFS for the game you’ll want to mod. You can do this using an emulator or a modded 3DS; this guide will cover both:

On 3DS you can do so by following this guide under the “Extracting RomFS from a 3DS game cartrige” or “Extracting RomFS from an installed title” sections depending on your game source. On Citra, Azahar (formerly Lime3DS) or Azahar this can be done by right clicking an installed title and selecting “Dump RomFS”.

Extracting Main Archives

Most of the game’s data (aside from alot of audio) is packed in main game and language archives; think of these as .zips. Now you can work with an unextracted .fa; especially if you don’t have alot of storage, but doing this will make your life alot easier.

Download Kuriimu2 and then open it; on some computers it takes a bit to open. Then click on File > Open (or Ctrl+O) and select the main game fa depending on the game this will either be:

  • yw_a.fa -> yw3, ywb, ywb2
  • yw2_a.fa -> yw2
  • yw1_a.fa -> yw1 Next, on the left hand side you’ll see a sidebar with the fa’s name. Right click that section, click Extract and then save to wherever you want. Finally, enjoy!

Using CfgBin Editor

First, download the latest version of opf’s CfgBin Editor this is a tool you will use very frequently so this tutorial will cover it; you can download it here.

Then download and set up the latest MyTags.txt, you can do so using this short guide.

If CfgBin Editor is already open, you’ll have to reopen it for the changes to apply.

Next open CfgBin Editor for the next steps:

  • Click on this link and click the download button to download this example cfg.bin (to be specific it’s YW1 EUR’s item_config.)
  • Optionally click on Settings > Languages and Settings > Themes to adjust the tool to your liking.
  • Then, open the file in CfgBin Editor using File > Open (or the shortcut Ctrl+O) You should then see something like this: Screenshot of cfg.bin editor Now lets practice a few edits! First and most importantly of all, let’s activate MyTags; this file is from Yo-kai Watch 1 so select YW1 under the MyTags select.

You should see something like this:

Screenshot of cfg.bin editor

  • Click “Add Root Entry” (under the search bar)
  • Now type the name of the entry you wish to create, for this example i’ll type “hello!”
  • Click “Ok”. You should end up with something like this:

Screenshot of cfg.bin editor If something is green, in this case the root entry/tree it means it’s unsaved. You can click the save button to save the change. Additionally, if an error occurs (i.e. you try to open something that isn’t a cfg.bin) in this case before screenshotting I made a root entry without a name.

Next you can right click an entry to see a list of buttons, I wont cover them as they are very self-explanatory, but I will show a picture! Screenshot of cfg.bin editor

Now lets do something practical!

Let’s add a new entry to ITEM_INDEX:

  • Click on the ITEM_INDEX root entry
  • Increase ChildCount by 1
  • Now we are going to add a child to the tree
  • Click on the arrow to expand the tree
  • Scroll down to the last entry (ITEM_INDEX_380 meaning the 381st ITEM_INDEX).
  • Right click it and click Duplicate
  • Now click on the newly created ITEM_INDEX we are going to edit the values/params
  • Increase the MainItemIndex by 1.

Generating CRCs

Alot of guide’s will ask you to generate a CRC32 for an ID i.e. ItemIDs. You can do this by going to a website like this and typing literally anything.

  • You should end up with something like 940fdaec, in CfgBin Editor you should add a 0x to the beginning so 0x940fdaec.

    Note: if you type the same thing in the website, you’ll end up with the same CRC32 and since IDs should be unique I’d recommend random keyboard spam like “dfhdsiuhudshodsh” (ofcourse don’t break your keyboard :P )

Now that you have an Extracted RomFS and a basic idea on how to use CfgBin Editor and generate CRCs, go and follow a different guide to start modding!