I personally didn't get this on Story mission 07 as I think I destroyed an item container or something in the area which voided the trophy. Going back to this I found that mission 05 of mission mode was also relatively easy as it's a circle with a few of these containers around and that's about it. If you take out the two fliers and aim strictly for Kokuto you shouldn't really have a problem. Both stages have very few options, so it really comes down to if you want to use Hollow Ichigo or a character of your choice for the trophy.