See Shugo Asano and Timothy Clark, The Passionate Art of Kitagawa Utamaro, exh. cat. [London and Tokyo: British Museum Press and Asahi Shinbun, 1995], cat. no. 490, where the authors note the extreme rarity of complete sets of 13, not the usual 12, images. The album is unsigned, but among the spicy commentary inscribed around the heads of the couples is a mention of an "Utamaru."
The first of Utamaro's three great erotic albums, Utamakura (Poem of the pillow), was sold in these Rooms, 22 September 2005, lot 24.