You're guaranteed to get a girl with 900 kobans in the epic. You only have a vague chance of getting a girl with 900 kobans in the event pachinko, but if you're incredibly lucky you could get all three girls.

If there was a certainty in getting a girl if you made three pulls on the event pachinko I would do it if I liked the line-up. As is, all I can say is that I'm glad they don't use the event pachinko for new events.