From Detective Conan Wiki

Victor Gollancz Ltd was a major British book publishing house of the twentieth century. It was founded in 1927 by Victor Gollancz (1893–1967) and specialised in the publication of high quality literature, nonfiction and popular fiction, including science fiction. Upon Gollancz's death in 1967, ownership passed to his daughter, Livia who sold it to Houghton Mifflin in 1989. Three years later, in October 1992, Houghton Mifflin sold Gollancz to the publishing house Cassell & Co. In December 1998 the Orion Publishing Group acquired Cassell & Co and turned Gollancz into its science fiction/fantasy imprint.

It published UK editions of various Viz Media properties, including Volumes 1-15 of Case Closed.