This article only details how to apply custom themes. If you wish to create one of your own instead, see the theme creation page instead.
Custom themes are a set of graphics and sounds that can be applied to your HOME Menu to give it a bit more personality. They are built on the same framework as the official themes that can be found on Nintendo's theme shop.
Custom themes are available on USA, EUR, and JPN firmwares. They are partially implemented but inaccessible on KOR firmwares, and entirely unimplemented in CHN and TWN firmwares.
Installation
Custom themes can be managed with a homebrew software called Anemone3DS.
You can scan one of the QR codes below to download and install the program using FBI. To do this, start FBI, then go to "Remote Install", then "Scan QR Code".
Copy Anemone3DS.3dsx to the 3ds folder on your SD card
Insert your SD card into your console
Power on your console
Section II: Extdata Setup
For Anemone3DS themes to work properly, you must create theme extdata. You can do this from the HOME Menu.
From the HOME Menu, tap the top-left HOME Menu settings button
Tap "Change Theme"
Set your theme to anything other than the default
Allow the 3DS to create the theme extdata
Exit the theme menu
Section III: Anemone3DS
Open Anemone3DS
If you don't already have a theme, press Right Shoulder to enter the QR code scanner, then scan a QR code from Theme Plaza to download a theme
Alternatively, you can place themes downloaded from the website (in .zip format) into sd:/Themes/. Create the folder if it does not already exist
See the top screen for instructions on what to do. Here are some examples of what Anemone3DS is capable of:
If you want to just install one theme with its background music, hover over the theme, press A to open the Install Menu, then press D-Pad Up
If you want to install one theme without its background music, hover over the theme, press A to open the Install Menu, then press D-Pad Right
If you want to shuffle multiple themes, press B to select the themes you would like to shuffle (up to ten), press A to open the Install Menu, then press D-Pad Down
Once you've made your selections, press Start to exit Anemone3DS