Submarine 707R

Story

In order to keep ocean peace, PKN was organized. It consisted of the state-of-the-art battle ships of various countries. However, they were raided during the foundation ceremony by the unidentified organization, USR, which plotted to conquer the world. They couldn’t be much for the submarine UX which was operated by Admiral Red of USR. But an old Japanese submarine, the 707 saved them, which was operated Captain Hayami at the risk of his life. One year later, succeeding to the 707, which had been ruined during the former fight, newly developed submarine, the 707 II, went for a sail.

Synopsis via AniList (English).