Dr. Hell, who observed the battle, correctly realizes that Sirène is part of the “Demon Tribe” that according to a legend ruled the Earth in prehistoric times.

Using his new flying fortress, Navarone, Dr. Hell and his henchman Baron Ashura follow Sirène to the Himalaya Mountains, were the rest of the demons are frozen.

Later, Akira goes to warn Koji about this but ends up mocking the Mazinger Z for being unable to fly; this leads to the two hot-tempered teenagers racing each other on motorcycles.

They manage to damage it before being driven off by Koji's ray gun; Sirène escapes by taking Shiro and Sayaka hostage.

The combined forces of Dr. Hell and the demons then attack the Laboratory; Devilman flies to help defend it, but is overwhelmed and captured.