The Attack on The Underground Castle Begins!! (Chiteijyou Kougeki Kaishi!!- 地底城攻撃開始!)

General Gururu came to Earth from Boazan to evaluate Prince Heinell's efforts in conquering the Earth. Meanwhile, the rebel slave's base in Alpine mountains was discovered and attacked. Dr. GOU Kentarou was kidnapped by Gururu right in front of Voltes V's nose. As Voltes chased Gururu, he led Voltes into Heinell's underground lair.