(From ebookjapan):

On a stormy night, Isamu witnesses a black phantom ship flying in the sky. He follows a man who has descended from the vessel and ends up at the Terada residence. There he finds four men terrified by a threatening letter from a man claiming to be Daisaku Arashiyama.

Gradually, Isamu's family's past is revealed. Is the phantom ship a friend of justice or an ally of evil?

The manga that inspired the 1969 anime film "Flying Phantom Ship", Ishinomori's early masterpiece with its SF elements and poignant adventure action!