I got the girl after spending about 1500 Kobans. I used about 300 attempts altogether. Reading the comments above, I can say that I was lucky. I'm sorry about those who had less luck than me.
Dear game developers give a chance to those who today are not lucky. It's simple. Add the condition - win (for example) 500 times and get a prize with a chance of one hundred percent. I'm sure this will make the players more joyful and you are richer and everyone will be happy.