Where can I get a 5th copy of the Summertime Mistress summer event craft essence?

I've already cleared part 1 of the summer event and bought up all of the Summertime Mistress craft essences from the event shop but that leaves me with only 4 copies of that craft essence. Is there something that I'm missing that I need to clear to get the 5th copy so I can max limit break the Summertime Mistress craft essence, or do I need to keep grinding in part one and just hope I get lucky and get the 5th copy as a drop item?