Keiya Iwai (born 1987) is a Japanese novelist. Born in Osaka, he completed graduate studies at Hokkaido University’s Graduate School of Agriculture. He made his literary debut in 2018 after winning the 9th Yasei Jidai Frontier Literary Award for "Eien ni Tsuite no Shōmei." His fiction draws on subjects ranging from science and sports to history and work, portraying the choices people make at turning points in their lives and the growth that follows. His best-known novel, "Eien ni Tsuite no Shōmei," follows a parent and child drawn to mathematics, exploring intellectual passion and the bonds between people.