Sparkle Hunting is a combo-reward system that gives you bonuses for decapitating three or more zombies at once. To enter Star Soul mode make sure you meter is full then hit . Juliet will start to glow and a special theme song will start to play. This mode allows you to score medals while showering yourself with rainbows and sparkles. During the duration of this mode any chainsaw attack you perform is an automatic one hit kill to any zombie. You must succeed in killing 7 zombies all in one swing of your chainsaw. Make sure you have a combo with good reach already purchased before going for this. Best combos for this is Holy Chainsaw(can be purchased for 999 medals), however Chainsaw Paradise and Chainsaw Full Swing can work too. There are several places this can easily be achieved:
Stage 3 (O' Bannon Farm)
Toward the end of this stage you will come to an open area filled with red and blue barrels. Destroy all these barrels immediately with your Chainsaw Blaster to clear the field. You will have to fight 3 waves of zombies here that will spawn from out of the ground. By the 3rd and final wave 32 zombies will spawn from the ground and come at you all at the same time. You can activate Sparkle Hunting mode or utilize your Holy Chainsaw combo but try to do so while all the zombies are grouped together. Nick Toss can also be used here by pushing down on and winning the roulette game. This move can dizzy zombies and turn them into 1-hit-kills. There should even be a Nick Ticket within the vicinity of the field across from the entrance.
Stage 5 (Cathedral)
Near the end of the stage, after rescuing the last classmate, you will slide down an elevator and into a large room filled with zombies. Nick will talk about a final battle and you will kick down a door. The next room will contain 32 zombies waiting for you. Try to get as many zombies as you can dazed by using a dropkick or pom-pom bash, then use the combo called "Holy Chainsaw" (, , , ,, ) to finish off the zombies. This combo can be bought for 999 zombie medals and is a great attack to use for this achievement.