Bride of Godzilla

Bride of Godzilla, alternatively titled as Godzilla vs. the Robot Daughter (Gojira no Hanayome) is a unmade kaiju film that was planned to be the third film in Toho Pictures' Godzilla franchise, being a direct sequel to Godzilla Raids Again. It was supposed to be written by Hideo Unagami.

Plot
Dr. Shida, a mad scientist, is a now either a widow or divorced since he lost his wife presumably to death or some other unknown cause, so he decides to create a robot in the likeness of his wife. During the time, Shida is creating the robot, Godzilla and Anguirus appear to wreak havoc upon the land, so Shida creates a giant feminine robot named "Robot Daughter" in order to fight these two monsters. In the original 1954 Godzilla film (Gojira in Japan), Dr. Kyohei Yamane explains that Godzilla was able to stay hidden because he lived in trenches, so Dr. Shida proposes that Godzilla and Anguirus originated lived in the center of a hollow Earth.

Dr. Shida goes inside the hollow Earth and discovers many members of both Godzilla and Anguirus' species respectively, as well as a race of gorgeous mermaids. He falls in love with on of the mermaids. Godzilla and Anguirus, along with a giant chameleon and a giant Archaeopteryx, the first bird-like dinosaur to ever be discovered, show in the island of Kyushu, Japan's third largest island. In order to stop these creatures, Dr. Shida finishes his Robot Daughter and sends her to defend Japan. She manages to defeat both the giant chameleon and the giant Archaeopteryx. She then defeats Anguirus by breaking his jaw and when fighting Godzilla, she was unaffected by his atomic ray breath, the character's most iconic and powerful ability.

After his loss against the Robot Daughter, Godzilla decides to fall in love with her and walks side by side with the naked Robot Daughter into a cave. One character literally and no joke, says "...it is the foreplay of love to be beaten." Godzilla later finds out that his "girlfriend" is actually a timed thermonuclear weapon in disguise and she takes him back to his ecosystem before exploding, presumably killing Godzilla and destroying the entire underground ecosystem, as well as killing other members of his species.

Why It Was Cancelled

 * 1) Toho Pictures did not feel that good about developing another Godzilla film in quick succession.
 * 2) The film's plot was too ridiculous.

Results

 * In 1956, the "hollow earth" concepts this cancelled film was up to expand appear to have been re-purposed for Toho Pictures' film Rodan, about two giant irradiated Pteranodons called Rodans, a male and a female, even though in the Godzilla films that came after it, featured only one Rodan, the male one to be exact. The "hollow earth" concept later resurfaced in 2019s Godzilla: King of the Monsters, to explain how Godzilla is able to be in the right place at the right time.
 * In 1962, 7 years after Godzilla Raids Again, Toho released the crossover film King Kong vs. Godzilla.
 * Hideo Unagami would later write the screenplay for the 1958 sci-fi tokusatsu film The H-Man.
 * Robot monsters, or kaiju, were introduced to the Godzilla franchise, with 1973's Godzilla vs. Megalon, which featured the size-changing Jet Jaguar and 1974's Godzilla vs. Mechagodzilla, which was the first ever appearance of the Big G's robot doppelganger, Mechagodzilla.
 * In 1998, retired Japanese vocalist Masato Shimon made a song titled Bride of Godzilla.