*Novice mode allowed*
Start up Slash mode and once stage one loads up, maximize your phantom energy. Do this by holding and shooting enemies at a close range. Once your energy has maxed out, generate some steel orbs. Do this by pressing and hitting enemies at close range. After you generate about 6-7 orbs, enter phantom mode with and press to shoot your steel orbs at various enemies. Shortly after that, the mid-boss will fly down, so aim all of your Katanas at the boss and shoot them at it with then immediately press to bomb and hold to shoot the boss. The boss will die within 2 seconds and the achievement will pop.