An expedition from Tokyo heads to Obelisk Island, where Keisuke Inoue Funazu, owner of Playmate Magazine, hopes to transform the rugged isle into a sprawling resort. The islanders greet the visitors with warmth, but the push for development casts a shadow over the welcome, hinting at a clash between curiosity, commerce, and the ancient rhythms of the place.
Two members, Tamio Kawachi Hiroshi Kurosaki and Yôko Yamamoto Itoko Koyanagi, ignore the pleas of a native boy named Saki and press into a forbidden cavern. They find a cave blocked by a fallen statue and uncover a giant egg nearby, a discovery that will tilt the balance between wonder and danger. The expedition scientists, led by Yuji Okada Daize Tonooka, are drawn into the mystery as the egg’s surroundings hint at something far older and more powerful than a simple wildlife encounter.
From the shell emerges a baby creature—what the locals call a “bird-lizard”—and the moment marks the beginning of a larger threat. The native boy’s warnings fall on deaf ears, and the hatchling is removed by the scientists, setting in motion a sequence of events that will test authority, ethics, and the limits of human control. Inside the caverns, two enormous Gappa parents rise from the subterranean waters beneath a volcano, unleashing a force that pushes beyond the island’s boundaries and into the wider world.
The baby’s survival becomes a global headline, drawing attention from researchers and military alike. Saki, the lone survivor from the initial calamity, is rescued by an American Navy fleet and brought back to Japan, where the extraordinary creature’s story captivates a public hungry for answers and spectacle. Public fascination soon gives way to fear as the Gappa phenomenon touches every corner of the planet, forcing scientists to confront the consequences of their curiosity.
Gappa’s presence triggers a cascade of dramatic events: two gigantic flying Gappa appear over Sagami Bay, and the parents wage a harsh, almost elemental, pursuit of their offspring. The monsters prove nearly impervious to conventional weapons, challenging the might of human technology and the resolve of those who seek to understand them. As cities tremble and the military’s efforts falter, the human players—Hiroshi, Itoko, Saki, and the expedition’s professor—grapple with a moral dilemma that sits at the heart of the crisis: is there a way to protect a society while honoring the bond between a creature and its guardians?
In the face of escalating danger, the group attempts a reconciliatory approach. They urge the island’s stubborn businessman, Funazu, to release the baby back to its parents and restore balance to the ecosystem. The negotiations are tense, and the outcome hinges on whether corporate greed can yield to a deeper sense of responsibility. The decision eventually leans toward returning Gappa to its kin, a choice that underscores a broader theme: the need to respect forces larger than human interests and the responsibilities that come with discovery.
After the tense standoff, the expedition team makes their way back to Obelisk Island, carrying with them the weight of what they have learned and the fragile hope that harmony between human endeavors and nature’s mysteries can be found, even in the wake of fear and destruction.
