MAZINKAISER VS. GREAT GENERAL OF DARKNESS

They strike without warning and instantly plunge the world into terror. The Great General of Darkness leads the underground Mycenae Empire in a bid to conquer Earth. The Mazinger Army falls before the seven generals under him, each of them leading an army of superior Warrior Beasts. Meanwhile, Archduke Gorgon is relentlessly pursuing Koji Kabuto, trying to eliminate him before he can reach Mazinkaiser. But a red light in the sky over Mt. Fuji portends the greatest battle in history! (Source: Discotek) — Description from AniList community (anilist.co).