User blog comment:Akrie/June 11th Events & Updates~!/@comment-26299169-20150616154154/@comment-24956068-20150618105440

Akrie, I guess they won't appear too when you have only a "little" remaining energy, thus means you'll die out of energy soon after purchasing. The calculation when 5 Crystals do appear or do not appear is quite difficult and I can only rely based on my experience.