As part of our seemingly annual Godzillathon, we're delving into some of the non-Godzilla movies in the Toho universe. Atragon features the sea dragon Manda, who later appears in Destroy All Monsters, and the submarine is also featured in Final Wars. But it's funny seeing how many titles the submarine/story has. Not entirely uncommon for Godzilla-ish movies, but this one's especially convoluted.

From Wikipedia. All emphasis mine.

Atragon, released in Japan as Undersea Warship... is a 1963 Toho tokusatsu film based on a series of juvenile adventure novels under the banner Kaitei Gunkan by Shunro Oshikawa (heavily influenced by Jules Verne) and the illustrated story Kaitei Okoku ("The Undersea Kingdom") by illustrator Shigeru Komatsuzaki, serialized in a monthly magazine for boys.

...It features ... the super submarine, Gotengo (or Roaring Heaven). While the name of the ship is recited as "Gotengo" in Japanese, it should be rendered as "Goten" in English; as the suffix, (go), simply denotes the object as a ship. For the English-language U.S. version, released in 1965 by American International Pictures, the supersub itself was dubbed Atragon, which had been shortened from Toho's own foreign sales title, Atoragon. Confusion over the actual Japanese title of the film by non-Japanese speakers, has led many to assume the original title...to be "Undersea Battleship"; unfortunately, the Japanese term for "Battleship"...is nowhere to be found in the title. Since ...(Gunkan) should be correctly rendered as "Warship", therefore, the film should be correctly transliterated as Undersea Warship.

On reading further, it seems "Atragon" is a contraction of Atomic Dragon, so i guess it does refer to Manda? If so, you'd think you'd give your titular character more screen time.

Update: I wrote this post after letting a little time pass and i had forgotten that the name Atragon, short for Atomic Dragon, actually does refer to the Goten-Go, not Manda. Regardless, Manda still should have gotten more screen time.