It's been a while... lemme see if I can dig it up.
*performs Advanced Search*
I believe it was this one:
You can also try Thouzers last dream stage. I used Raoh with Ujoken effect boost and I quickly recieved the trophy for 5k Ujoken kills. Ended the stage with a 3.5k kill count in about 30 minutes.
No wait, duh it's on the second page: What is the best scenario to farm kills?