Looking for a Japanese UFO Movie with a mission to Venus

Question

This has been a old live-action movie from Asia, most likely Japan. I've seen it some time in the late 80's and I think it's been black/white only.

• Earth is invaded by UFOs (small and round, like flying balls), coming from Mars.
• Japan (I think) built some kind of super spaceship, initially hidden within some secret port in some kind of island/mountain.
• The spaceship looks similar to a classic battleship, but with an added drill below the front.

- In the movie's finale it's revealed that this is some kind of super weapon/bomb that has to be manually piloted by someone. When launched it starts rotating and flies (formed like a bullet but with the drill/corkscrew head).

• To defend earth, the ship is sent on a mission to Venus, where the UFOs seem to originate. I don't remember the specific reason or conclusion here.

• The ship starts underwater or launches from the mountain on the island, then taking off and fighting UFOs while leaving Earth's atmosphere.

Answer 1

It appears to be Wakusei Daisenso [1977] (or 'The War In Space'), as described by imdb:

The movie starts out in 1988 with pilot Koji Miyoshi's return to Japan in response to electromagnetic interference that is plaguing the world following a comet scare. Miyoshi is quickly reunited with old friends and acquaintances upon his arrival, although the reunion is cut short as UFOs began to appear all across America as the UN's Space Station Terra is also destroyed in orbit. This series of events prompts Miyoshi to meet with Masato Takigawa and request that the United Nations Space Forces' Gohten Project - construction of the UNSF Gohten, is completed. The request falls on deaf ears until the aliens from the distant planet of Yomi in Messier 13 who have been behind the recent disturbances bungle a plan to kidnap Takigawa, at which point work on the Gohten commences amongst global chaos from attacking Hell Fighter UFO's. Following a fierce battle at the Gohten’s base, the craft is finally launched as it makes its way to Venus, the suspected location of the invaders’ base of operations, to put an end to the alien threat.