hokkaido 4 day pass?

Hello

There is a post about a flexible 4 day pass for Hokkaido but I can't find what that one costs. If I take the 5 day pass I guess it's not a problem to activate it whenever I want within a 3 months period? I wanted to order that one but got scared because of that 4 day pass that says that you can't change the day of use.

Thanks in advance

1. Vlieks