On a physical 3DS, use the FBI homebrew app to install the DLC CIA. On Citra, use the "Install CIA" option in the top-left menu.
The downloadable content for Etrian Odyssey Nexus consists of cosmetic portraits, background music (BGM) tracks from older games, and quest-based items that ease the traditional grind. Unlike some games where DLC alters the main story, the Nexus DLC is designed to heighten customization and offer optional gameplay shortcuts. Key DLC Pack Contents Etrian Odyssey Nexus- DLC 3DS -EUR USA- CIA
Because it was designed as a farewell letter to fans, Atlus packed the game with nostalgic throwbacks, many of which were distributed as specialized DLC. Comprehensive Breakdown of Etrian Odyssey Nexus DLC On a physical 3DS, use the FBI homebrew