That's more or less what I concluded.
It is at least misleading in context, that you don't get any items in a draft pachinko - or as you say: a trap. I just wonder, why the game designers would do something like that. If i would consider spending real money for the game, i would want to spend it on stuff, that is what it promises to be. Or more clearly put: Realising, that there are Koban-Traps in this game, is a great demotivator for real-money-investments.