Complex sentence: Despite this, it scored high ratings with the younger, more casual audiences, and the show's first opening theme "Anime Ja Nai" became extremely popular with anime fans and is sometimes mentioned as one of the most momerable anime songs of all time.
Split into simpler sentences: Despite this, it scored high ratings with the younger, more casual audiences. And the show's first opening theme "Anime Ja Nai" became extremely popular with anime fans and is sometimes mentioned as one of the most momerable anime songs of all time.