Guide by True-XenoBlade at 16 Jul 2013. Link below.
https://www.truetrophies.com/t52744/lucky-me-trophyThis Trophy is luck based
The Lucky me! Trophy is an easily enough obtained Trophy, despite it being luck based. All you have to do is go to the Shopping District North on either a day off or after school and purchase a drink from the Northern vending machine next to the road. The drinks are fairly cheap and early game can provide an adequate SP regain in battle providing you stock up every Monday when the refill.
When you purchase a drink (any of them will do, doesn't make a difference) you have a small chance to win a free prize (which is just another drink) A small beeping sound will begin in the background once you buy one and when you win a free drink it pops up on the screen along with the trophy. If you make an effort you will get this Trophy without having to bother much as the drinks are so cheap compared to the money that you can obtain.