The final cut scene is played after having beaten Namoris. It's the end of the story, anything beyond is optional end game content. Dark Kjayudo is the toughest mob, but there won't be another ending. You can always go back, battle more enemies, improve your character stats if not fully maxed out, etc.
Rainbow Skies is finally available. Download it on the PS Store for PS4, PS Vita and PS3.
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