Return Of The Giant Monsters (1967)

Starring Kojiro Hongo, Kichijiro Ueda, Reiko Kasahara, Naoyuki Abe, Taro Marui
Directed by Noriaki Yuasa
(actor & director credits courtesy IMDB.com)

Gamera the prehistoric turtle monster returns in time to take on a new monster, Gaos, awoken from an ancient slumber by a series of volcanic eruptions.

The third Gamera film features weaker special effects than the first two but finds Gamera taking on full-fledged hero status, battling Gaos, who menaces the skies and emits destructive sound wave beams from its mouth, slicing aircraft in two.  The film features the return of original director Yuasa, and another young boy for Gamera to rescue and for children in the audience to identify with, after children were curiously absent from the grimmer Gamera Vs. Barugon.  The results are good fun, although a lesser film than its predecessors.