On Wester Island in the Pacific Ocean, a large statue of mysterious origin (called the Devil's Whistle) is located by scientists.

The statue appears to be the source of the outbreak, as it makes a continuous piercing sound, driving many of the crew members insane.

He pulls himself up with his tail using a large rock, then removes the embedded quills from his limbs and is finally able to fly after Jiger.

Meanwhile, Jiger is actively seeking the statue, because it is making a horrible ringing sound that is causing her tremendous pain.

Scientists are beside themselves as Jiger displays another weapon: a heat ray that vaporizes not only flesh, but entire city blocks.

Jiger extends a stinger from her tail and inserts the barb into Gamera's chest, laying an egg inside his lung.

One of the scientists served as a zoo director and realises that the spot might not be a fast-spreading cancer, but actually a parasitic infant Jiger growing inside Gamera.

Communication is established with the kids and they enter Gamera through his open mouth, and after almost going into his stomach, they arrive at the problem lung.

They rig up large speakers to keep Jiger at bay, as well as figure out that power would have to also be run into Gamera, who seemingly cannot recover on his own.

The children make a final trip inside Gamera to hook up a set of power lines directly to his heart.

As boys magazines at the time had stories on ancient civilizations that were popular, Nisan Takahashi's early script, titled Gamera vs.

Giant Demon Beast X (ガメラ対大魔獣X, Gamera tai Dai Majū Ekkusu), constructed around an ancient monster from the lost continent of Mu.

Reportedly director Yuasa coerced then Daiei president Nagata Masakazu to fork over an additional allotment of 30 million yen (approximately 100,000 US dollars at that time) to beef up the effects budget.

[1] Keisuke Sawada, the young Expo 70 worker who befriends the children and acts as their guide, was played by then 20-year old Ryo Hayami, under his first stage name Sanshiro Honoo.

[4] Image Entertainment released the American version of the film in 2004 on DVD as a double feature with Monster from a Prehistoric Planet.