Gōkan

''' (合巻) is a variety of Japanese woodblock printed literature under the broader category of picture books known as ' (草双紙) produced during the late Edo period from circa 1805 to the late nineteenth century. It is a successor of (黄表紙), which featured adult themes that changed significantly in content and style following censorship imposed by the Kansei Reforms. However, in physical form and production much remained the same between the two, such as large images with whitespace filled with narrative text and dialogue composed largely of kana.

are typically much lengthier works than their predecessors, with the longest extant example being, which contains ninety chapters produced between 1849 and 1885. Because of the lengthy nature of the works, individual books were often gathered together and bound into larger volumes, which is reflected in the Japanese term for the genre (lit. "bound volume"). , along with the rest of the varieties, belong to the literary genre of Edo literature known as gesaku (戯作).

History
The first piece that explicitly utilizes the term is  written by Shunsuitei Genkō. Although itself classified as a by the Waseda Classics Database, the complete story is a collection of ten books bound into a single volume as shown on the cover, giving a name to the new process. The first author who laid claim to the origination and proliferation of is Shikitei Sanba. Although not the sole progenitor of, his work contributed to the staying power of the works in the coming decades.

By far the most studied and best-selling example of is Ryūtei Tanehiko's. Published from 1829 until 1842 by Senkakudō, the story is a parody of Murasaki Shikibu's Tale of Genji. The setting changes from the Heian Period to the Muromachi Period, with the titular Genji becoming Ashikaga Mitsuuji, the fictional son of Ashikaga Yoshimasa.

By the Meiji era, the production of was in significant decline due to the emergence and subsequent popularity of newspaper serials. A notable late work was, written by Kanagaki Robun. Initially serialized in his own, the work was quickly transferred over to the format for a lengthier and more in-depth story. This late flourishing of was primarily reserved for  (毒婦) literature, outlining stories of murderous sensational women.