Daikyojû Gappa 1967

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.

The Director: Hiroshi Noguchi
The Writers: Ryûzô Nakanishi, William Ross, Iwao Yamazaki
Music by: Seitaro Omori

Film Trivia

There was an urban legend that Nikkatsu's international English prints originally had a racist line, "The monsters are attacking Tokyo. Fortunately they are attacking the Negro section of town" (and that the line was changed). This was untrue.
This is the only monster movie (kaijû eiga) released by Nikkatsu. Unfortunately, after this film was released, the company nearly went out of business.