Sengoku Gyouha Dullahan: Kagen no Keishousha

The story is set in a parallel world of the Sengoku era. Date Masamune rides a giant robot called Ouryuu. However, the robot is too strong for the young Masamune to control, which leads to the death of many people. Fearing the power of Ouryuu, the other daimyo form an alliance against Masamune in order to destroy Ouryuu.

(Source: MU)