My first time through it was definatly seymour flux but i figured out a great stratagy for him then when i got to yunalesca i thought it was eaasy but it turned out there was more then the first form so i blew all my ODs nowadays there really isnt a "hard boss" storyline wise i make it a point to capture monsters as fast as i can because i like to fight the original creations i have beaten them all at least once but very few more then that, sadly i dont have the international version but i wish i did i love the game and really wanna be able to fact the dark aeons/penence.