Takashi is a classmate of Asumi in junior high school. He was also her classmate in elementary school but he was too sickly to regularly attend school. His story is mainly shown in the flashback episode/chapter, "Asumi's Sakura".  (Source: Wikipedia)

In a Tokyo of the not-too-distant future a young girl looks up to the stars with melancholy in her heart and hope in her eyes. Thirteen-year-old Asumi Kamogawa&rsquo;s life has been tied to those stars; her future may very well be among them. And she is not alone... Asumi is one of many young people with ambitions to some day head off to space for Japan&rsquo;s first manned mission. 
Before liftoff, like any true astronaut she must show the right stuff and overcome odds to pass numerous physical and mental trials if she even wants to be considered in the running for a rare spot in the elite Tokyo Space School.
 
(Source: Kodansha USA)

When Kamogawa Asumi was just a baby, her mother was grievously injured when a rocket crashed to the ground. Five years later, having been in a coma all the time, Asumi's mother finally dies, and the little girl struggles to come to terms with the death of a mother she barely remembers. In the midst of her turmoil, she meets "Lion-san", a strange figure wearing a lion mask and claiming to be a ghost. Lion-san helps Asumi to bury her mother's ashes, and finally, Asumi reaches her own decision: "When I grow up, I'm going to be a rocket pilot."
 
(Source: Anime News Network)

Takashi Shimazu