Chiteikoku no Kaijin  

The Mysterious Underground Men Satan's House, 地底国の怪人

The manga Chiteikoku no Kaijin portrays the story of a young scientist named John and his companions as they battle against an underground organization that aims to seize control of Earth. To fulfill his father's last wish, which was to travel through the earth, John constructs a high-speed, secure train capable of penetrating the earth's surface. During their journey, John encounters Mimio, a rabbit with human intelligence, and they join forces to reach the center of the Earth in a newly constructed rocket train. However, upon arriving at the underworld, they discover that it is ruled by a queen who seeks to conquer Earth. Despite this setback, John and his friends, including Uncle Bill, manage to escape back to the surface. They then construct another rocket train and return to confront the underworld's ruler once more.

Chiteikoku no Kaijin was published in English as The Mysterious Underground Men in hardback by PictureBox on November 30, 2013, as the second volume in their "Ten Cent Manga" series.