Much has been written on Japanese woodblock prints, book illustrations and paintings of the Edo period known as Ukiyo-e, but often neglected in any discussion of this rich artistic tradition is the genre of erotic imagery. Many celebrated Ukiyo-e artists such as Suzuki Harunobu (1725?-70), Isoda Koryusai (1735-90), Torii Kiyonaga (1752-1815), Kitagawa Utamaro (1753-1806), Katsushika Hokusai (1760-1849), Keisai Eisen (1790-1848) and Utagawa Kunisada (1786-1865) created significant numbers of sexually explicit compositions that are today collectively referred to as shunga, or 'spring pictures'. As objects deemed injurious to public morals, shunga were banned by the Tokugawa government. Faced with the challenges of working in an illegal genre and the demand for shunga by a voracious public, shunga artists exhibited an innovativeness and creativity in their work that would be remarkable in any age.