This achievement/trophy can be earned by defeating Urizen in the Prologue.
You should first complete the game so you can have much more health and Nero's Devil Trigger transformation. This will allow you to power through that protective crystal, BUT you should be very careful as he will still deal with some punishing moves, even on Human Difficulty.
The method I used was to be a ranged fighter until I got the crystal down. To do this I used my charged up gun-shots and the Pre-Order bonus Megaman Blaster. This can be done much easier in Heaven or Hell difficulty as the boss will only need to be hit once to die.
Here is a video guide of how I achieved this.