Kyutaro Hoshino is a character from Planetes.
Kyutaro Hoshino is Hachimaki's younger brother, currently a high school student on Earth and an amateur rocket maker. Kyutaro considers Hachimaki an "insincere astronaut", as he feels that Hachi's role as a debris hauler does not warrant the title and the connotations that come with it. This echoes a sentiment expressed early on by (a completely inexperienced) Ai Tanabe. Any conversation between the two almost always degenerates into a brawl as they argue over their differing perspectives on space. Kyutaro hopes to eventually become an engineer to design larger and more powerful rockets that would allow humanity to push its boundaries further into the solar system.