Ninety-Nine Nights, is a action/strategy game currently being develop by Q Entertainment and Phantagram for the X360. The game is set in a middle earth style world, and is in the spirit of games like Dynasty warriors and Kingdom Under Fire. I think its more of a hybrid, personally. The game has up to 5,000 enemies on screen at any given time. I know that doesn't seem like much compared to Ikusa Gami, but consider the fact that the enemy AI and animation are suppose to be better and more dynamic.
http://www.n3-game.jp