Goes through Ketsui Death Label and unlocks Extra Mode.
ROM: Ketsui - Death Label (2812) (JP) SHA1: 6073F952622FC2A380973BBA9116D33403BB8CB0
Bizhawk 2.5.2
Firmware on. Blank out any firmware settings in DS > Sync Settings: check "Boot to Firmware", and click Default on the bottom left to reset all settings.
You need both ARM7, ARM9 and your own firmware. Your firmware will not be accepted by BizHawk: right click on the NDS "firmware" entry, check "Set Customization", then import your firmware.
firmware.bin SHA1: AE22DE59FBF3F35CCFBEACAEBA6FA87AC5E7B14B (but should sync with other firmwares)