While I cannot provide direct, unofficial download links to copyrighted ROMs, you can find the Japanese ISO through established preservation sites:
A standard dual-layer ISO for this game is approximately 7.9 GB . Legality and Nintendo's Stance dairantou smash brothers x iso download
The Japanese version features an "X" in the logo rather than the word "Brawl". It is region-locked While I cannot provide direct, unofficial download links