Legend Of Dinosaurs And Monster Birds 1977 Screenplay by Masaru Igami, Isao Matsumoto and Ichirô Ôtsu, directed by Junji Kurata.
Made by Toei Company, the studio was inspired by Jaws, the film did poorly in the Japanese theaters but was a block buster in the Soviet Union. It was known in the US as The Legend Of Dinosaurs and it was used in the last episode of the first season of Mystery Science Theater 3000 which was produced by KTMA. That version was chopped up a good bit, the original movie got a US DVD release in 2007 from Media Blasters and that's what I watched.
A woman falls into a cavern, in the Aokigahara region near Mount Fuji, she awakes to find fossilized eggs, one of which hatches. She runs off and scares a construction crew with her hysterics. A geologist called Takashi goes to take a look, while hiking around Mount Fuji he's knocked out and wakes up in the cabin of a family friend. Takashi continues his hunt for the eggs, on the way he meets an old girlfriend Akiko. She's there with her friend Junko, a scuba diver, who wants to dive in the lake where a couple in a small boat went missing.
A diver is injured in the lake, livestock have gone missing, wild theories of living dinosaurs are tossed out to the dubious public. Well, turns out it wasn't a dinosaur, it was two, one of them a plesiosaurus and the other a rhamporhynchus. The pair battle it out and the volcano erupts killing both dinos. It's a bad day on Mount Fuji and the movie ends on a cliffhanger.
I was much more entertained by the movie than on MST3K. It was like seeing a whole different movie, the MST3K version had so much trimmed out of it. It's a more adult film than I thought, there's a bit of gore, mild by today's standards and a brief bit of nudity. I'd watch it again.
I'm not sure why it did so poorly in the Japanese box office. It was Toei's biggest budget, $2.8 million and it didn't even get a third of that back in receipts. It never got released theatrically in the US but it was released to TV in 1987.