Just to clarify this one:
The bullets you need to cancel to unlock this particular achievement are not the classic Kakusei purple ones; those DO NOT COUNT.
Only RED BULLETS count. I unlocked it using Zeshikai Over (holding B + no gems) bullets because all bosses double their shoots in this mode. Chances are that Kakusei Over (tap B once + no gems) red bullets also count but I couldn't say for sure.