An expedition in the South Pacific lands on a tropical island where the natives worship the mysterious deity Gappa. An earthquake opens up an underground cavern and a baby reptile is discovered inside. The natives warn the foreigners to leave the hatching alone, but they don't listen and take it back to a zoo in Japan. Soon after, moma and papa Gappa start smashing Tokyo looking for their kidnapped child.
You can now watch Gappa, the Triphibian Monster online on the following streaming providers in the United States.
| Writing | Ryuzo Nakanishi | Screenplay |
| Sound | Seitaro Omori | Original Music Composer |
| Art | Kazumi Koike | Set Designer |
| Camera | Muneo Ueda | Director of Photography |
| Directing | Haruyasu Noguchi | Director |
| Writing | Gan Yamazaki | Screenplay |
| Editing | Masanori Tsujii | Editor |
