Throughout their time at the academy, astronaut candidates must overcome numerous physical and mental trials. Readers discover from a pre-serialization story that Asumi's mother dies following the Lion disaster, but this is not known to Asumi's friends until Kei discovers the obituary listing in a newspaper article. Marika is revealed to be the genetic copy of a deceased Marika Ukita despite a standing ban on human cloning. Fuchuya suffers from red-green color blindness after his eyes are exposed to an exploding firework at close range in a childhood accident. Unknown to the group, Shu suffers from hereditary hemoptysis (coughing up of blood) and dies from the condition soon after his selection as an exchange student to the American space program. This tragedy reveals Kei's feelings for him, which she keeps hidden for much of the series.