DIJI-NES is a high-performance NES (Nintendo Entertainment System) emulator designed to run on the ESP32-S3 microcontroller. It emulates the 6502 CPU, PPU graphics, and APU audio with cycle-level accuracy, supporting mappers 0-4 (NROM, MMC1, UxROM, CNROM, MMC3). The system renders 256x240 pixel frames at near-60 FPS to an ST7789 display via LovyanGFX and outputs audio through an I2S DAC (MAX98357A). It features a dual-core architecture: Core 0 handles audio generation and display DMA, while Core 1 runs the emulation loop. The firmware includes a ROM browser menu, save/load state support, volume control, and a particle boot animation. The codebase demonstrates deep NES hardware knowledge and aggressive optimization for embedded systems, including IRAM placement, lookup tables, bank caching, and frame-skip logic. While the main application is tightly coupled to the ESP32-S3 platform, the core emulation components (CPU, PPU, APU, cartridge) are well-isolated and could be extracted for reuse in other NES emulation projects.