Does a US Oblivion Disc Work on a Japanese Xbox 360? No, Region-Locked

No. The Xbox 360 is region-locked for physical game discs. The Elder Scrolls IV: Oblivion was released with distinct region codes:

• NTSC-U/C (Americas): Region 1
• NTSC-J (Japan/Asia): Region 2
• PAL (Europe/Australia): Region 3

A Japanese console (NTSC-J) will reject a North American disc (NTSC-U/C) with a "Disc unreadable" or "Region error" message. The console's region is hardcoded; it cannot be changed via software settings.

Workarounds (Not Officially Supported)

• Japanese Disc: Buy the Japanese release (Oblivion: The Elder Scrolls IV, CERO Z rated). Fully compatible, Japanese text/voice by default (English options may vary).
• Region-Free Modding (JTAG/RGH): Hardware modification allows running unsigned code and region-free backups. Risks: Bans from Xbox Live, potential brick, requires soldering/technical skill. Not recommended for average users.
• Xenia Emulator (PC): Play the US ISO on a capable PC. Best performance/visuals (4K, 60 FPS, mods).
• Xbox One/Series X|S Backward Compatibility: Oblivion is backward compatible. A US disc works on a US console; digital purchase is region-locked to store region. A Japanese Series X|S plays the Japanese digital version.

Recommendation: Purchase the Japanese physical copy or the digital version from the Japanese Microsoft Store on a modern Xbox.