Dying and continuing resets your score. Playing in Arrange 360 mode makes this easier as the games shoots for you, also rubber banding the right trigger will allow you to keep your shikigami out without holding down the trigger yourself. So all you have to worry about is dodging and moving your shikigami around you should get this somewhere in stage 5 or 6, depending on your coin combo and how many times you have been hit.
When you get hit; even slightly will drop your coin-combo which means your score will not increase as fast. Best way to ensure you get this achievement it is to do a nearly flawless run. This involves practice and patience but no were near as much as "The Subjugation of Guwange-Sama" and "True Diabolical Power". Just keep practicing and memorizing the different bosses patterns.