Nice, I like the story and the setup. Good prologue.
Some notes on the gameplay, I imagine you might already be thinking about some of these suggestions.
The Rock, Paper, Scissors style isn't bad. But I think some allowances should be made to be less grindy. Such as if you're high enough level above them, then perhaps even if you have a tie some reduce damage will go through, get a possibly of seeing the next action or something of that nature to reduce grindyness when you're high enough so it's less guess work.
Skills, Any sort of skills just to mix it up a bit. The same 3 options get's a bit repetitive. For example "Silence" which removes the enemy from being able to use Magic Attacks (Paper) for x turns. Or "Reflex Boost" ties become success for x turns. Stuff like that to learn, you have Energy as a stat already too.
The Store should post prices even if you don't have enough coin. The double EXP potion doesn't show up until you have 50 coin. I mistakenly was wondering about that since it was mentioned in story but not visible in the store, so I just stocked up on food and potion to spend my coin instead of the better option of saving till I got 50.
But all in all, I love it. Was fun, Pictures were nice. It's a fantastic initial release that's quite long.