Kaku-San-Sei Million Arthur is a King Arthur related card battle game going to smartphones from Square Enix. Artists illustrating the cards include Takehito Harada (Disgaea), Kohaku Kuroboshi (Sky Girls), Yuichi Tanaka (A Certain Magical Index), BUNBUN, and VOFAN (Time and Eternity), with an animated opening by J.C. Staff (Shakugan no Shana).
If only the game wasn't just focused on card battles...
looks interesting for a cellphone card battle game