Ok, this is puzzling me.

The tutorial showed me that I can asign more than 1 hero in a party, and I had 2 slots available, but after entering the 3rd stage I only had 1 hero,and the slot that was previously open, now it has a nutaku glod price. What the hell game? why did you make me add another hero to the party if I still have to use a single one everytime?