Ukiyo-e 浮世絵
Edo-period paintings and especially woodblock prints of urban life, actors and beauties, which English Wikipedia names among the sources Itō Seiu drew on.
Ukiyo-e means “pictures of the floating world.” Kotobank explains ukiyo as this present, worldly life with an undertone of pleasure, and English Wikipedia notes that it punned on a Buddhist word for the world of sorrow. The genre covered painting and woodblock printing. Kotobank dates the prints from Hishikawa Moronobu in the later seventeenth century, and both sources mark 1765 as the start of full-color “brocade” prints around Suzuki Harunobu. Subjects ranged from beauties, kabuki actors and sumo wrestlers to legends, landscapes and erotica. Production fell steeply after 1868, when rapid Westernization brought competition from photography and woodblock printers turned to news work.
English Wikipedia names ukiyo-e, together with kabuki, among the sources Itō Seiu drew on.