Although "Twin Spica" began serialization in the October 2001 issue of Media Factory's "Comic Flapper" magazine, its lead character Asumi had appeared in Yaginuma's debut work "2015:Fireworks". This short story published in the July 2000 issue of "Comic Flapper" also introduced readers to Asumi's father, her elementary school teacher Yuko Suzunari, and the astronaut ghost Mr. Lion. Four additional short stories that predate the series also feature Asumi as the central character: , , , and . These slice-of-life stories eventually served as prequels to "Twin Spica".