Complex sentence: Though Yuya succumbed to Zarc's control and completed his original self's resurrection, his friends refusing to accept that he has ceased to be, it took Zuzu's presence through Ray to enable Yuya to help her and Riley defeat Zarc.
Split into simpler sentences: Though Yuya succumbed to Zarc's control and completed his original self's resurrection, his friends refusing to accept that he has ceased to be. It took Zuzu's presence through Ray to enable Yuya to fight against Zarc's control and help Ray and Riley defeat Zarc.