@A patriotic military adventure story for boys by Hirata Shinsaku, a military commentator. It first appeared in Shônen Kurabu [Boys' Club].
@An Arctic expeditionary ship Hokutomaru on its way to find a secret region in the Arctic is attacked and sunk by the countries A and B. The protagonist Hiroshi and other crew members on board are saved by a battleship Takachiho, and they succeed in discovering the secret region. Military knowledge, actual names of places and battleships are skillfully woven into the narrative, which make it truly realistic. For example, Takachiho was a name of the battleship which really existed. In the latter half of the story, Hiroshi finds the lost battleship Unebi in the secret region and encounters the frozen body of his grandfather who was among the crew of the ship. The disappearance of Unebi was also a well-known fact at that time.
@The story attracted many readers together with powerful illustrations. However, it cannot be denied that the book played a role in instilling a war regime on children.
@A reprint of the original was published by Kôdan-Sha in 1970.