宇宙兄弟＃0

Four years before the main Space Brothers story begins, Mutta Nanba is stuck in a dead-end job at an automobile company while his younger brother Hibito trains as an astronaut in the shadow of two legends, the J. brothers, Brian and Eddie. Hibito is picked as Brian's backup crew member and pupil. When Brian dies on a failed return flight from the Moon, the message he leaves behind becomes the thing that keeps Hibito going, and in time pulls Mutta back toward the dream he had given up.