NINJA GAIDEN Σ

Ultimate Techniques are performed by holding down the Y button. Ryu will first get a glow to the weapon, then a blue effect on the ground in addition and then finally the blue effect will turn red. It is these red ones that count for this achievement, as they are fully charged. The best way to do this is to kill 2 enemies but not collect their (Yellow) Essence, then hold Y. Ryu will absorb the essence and instantly fully charge a UT. Blue or Red Essence only need one orb to achieve the same effect. Enemies killed with UTs will drop double the amount of Essence, so it is in your interest to use them. The best weapons to do this with are the War Hammer, Dabilharo and the Unlaboured Flawlessness, as their UTs all hit a wide area. This is very likely to come naturally as part of a playthrough, especially if you are making use of UTs in regular combat or to complete the Ambushes.