I just got my first my first key sphere as a gift from Rin, but I want MORE. I want my characters to get the extra goodies behind those doors (like +8 def for Lulu and some good power ups for Yuna) and so I'm waiting until I get more before I move them along the path. It's been a while and so I can't remember when I can get some, if at all. Currently I am at the top of Mushroom Rock. I haven't used the first one yet because I know Kimhari will need it sooner or later and I don't want him to get stuck.