21st Century Adventure

Isami Nishitani's parents are killed in explosion onboard the Luna Park I, the world's first stratospheric flight rocket ship. His father leaves behind a rabbit's ear said to increase the brainpower of a human being. That ear is transformed into an anthropomorphic rabbit, Mimio. Nishitani plans to avenge his parents' deaths by being the test pilot for the earth-penetrating train Luna Park III - in which Mimio is also scheduled to board.

The third take of The Mysterious Underground Men by Tezuka, and the final appearance of Mimio.