Complex sentence: On their journey, they meet Sheena Fujibayashi who comes from Tethe'alla, a world parallel to Sylvarant, and how the two worlds vie for each other's mana through the journey of regeneration.
Split into simpler sentences: On their journey, they meet Sheena Fujibayashi who comes from Tethe'alla, a world parallel to Sylvarant. She tells them about how the two worlds vie for each other's mana through the journey of regeneration.