Izumi Shikibu (born c. 976), one of the Thirty-Six Medieval Immortal Poets (Chūko Sanjū-rokkasen), is a writer and a poet from the Heian period (794–1185). She wrote various types of waka poems from both female and male perspectives, drawing on her broad knowledge of classic Chinese and Buddhist texts and deploying a wide range of emotional expressions. Her waka poems were so popular that they were incorporated into imperial anthologies, such as Goshūi Wakashū (1086). One of her poems is also included in Ogura Hyakunin-isshu, the anthology of 100 waka poems written by 100 eminent poets. In addition to the poems, this talented woman wrote Izumi Shikibu Nikki ( Izumi Shikibu Diary), reputed to be one of the major works of Heian diary literature. Known as a passionate woman who had romantic relationships with many noblemen, including two sons of Emperor Reizei (950–1011), in her Diary Izumi Shikibu wrote about the course of her love affair with Atsumichi Shinnō, the fourth son of the emperor.