Sora Iro no Tane (そらいろのたね, lit. The Sky-Colored Seed or The Blue Seed) is a 1964 Japanese children's picture book by Rieko Nakagawa and illustrated by Yuriko Ōmura. It was serialized by Fukuin Kanshoten in their Kodomo no Tomo (こどものとも) magazine in 1964, and then published as a book in 1967. Since being published in the magazine, it has been in continuous publication and had sold over a 1.7 million copies in Japan by 2010.