The Big Wave (1961)

Yukio a farm boy and Toru a fisherboy live in a small Japanese village that is periodically threatened by a volcano on one side and tidal waves on the other Yukios younger sister Setsu follows then and dreams of becoming a pearl diver Toru is preparing to go fishing with his father when a bell tolls and a danger flag is hung high on the hill behind the village to warn of an impending tidal wave by the village patriarch known as Old Gentleman