So, title is obvious. My suggestion for this game is for it to show the pull rate percentage whenever we are pulling. Also, to increase by fractions with each pull. Fire Emblem Heroes has that, in which you know exactly the odds of getting a 3, 4 and 5 stars hero. Also, for every pull you do without a 5 stars, you get a .5% increment in it.
I think this would be an awesome thing to make the game better and more transparent.