Pirates have kidnapped Zero in an attempt to finally defeat the notorious Captain Harlock. Harlock is bound by a promise to his friend Toshiro to protect his lab on a strange mushroom planet. Fates collide as Zero, Harlock, Sylviana and the pirate Hunter all pursue their own agendas during one decisive battle. (Source: Anime News Network)
Watch Young Harlock wo Oe! Cosmo Warrior Zero Gaiden episode 1 online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.