Samurai Warriors 2 Empires?

Ok I give up searching the web, I shall ask here & see what I get.

I rented Samurai Warriors 2 Empires for Xbox 360 and I am trying to get all the achievements before returning it. I need 5 more and one of those I am unsure how to get to. It says “In Empire Mode, play the special stage ‘Osaka Campaign’ and save your game.”, but I am unsure which battle has this. I have searched the web and all I find are sites listing the achievements. Anyone know?
I am also frustrated that I played with Hideyoshi Toyotomi, got 1000 kills in one battle and still didn’t unlock the “Most Valuable Warrior” achievement. He has a little badge next to his name that says 1000 now though.