The Gotengo, or as it's known better in the West, The Atragon - the flying submarine seen in the 1963 film of the same name.
This lovely little model, released in 2003 by Bandai and similar in size to the small Konami range of Sci-fi models, was given to me by my blog friend, Will Schwartz, who is a big fan of Japanese Sci-fi movies.
I first watched the movie during the late sixties at my local ABC Cinema as part of their Saturday morning matinee for kids - remember those?
I was really taken by the design of the sub, with it's flying capability and it's drilldozer front, something quite common in Japanese mecha. As the film came out in 1963, it does pre-date the Thunderbird Mole which would have appeared in 1965.