The Mega CD was first shown in Japan at the Tokyo Toy Show in 1991 and later released on December 1st for ¥49800. In the first year of release in Japan, Sega sold 100 000 systems, but would have sold more if the price wasn't so high. Sega of Japan did not inform Sega of America about their Mega CD until a few months later. It was first shown in the US at CES in Chicago, Illinois in March 1992 and announced for release in November. It was released earlier than this, on 15th October in America (for US$299) but not until Spring 1993 in Europe where it was very expensively priced and so only 4% of European Mega Drive users owned a Mega CD in the end. UK had the biggest following of the Mega CD in Europe when it debuted in April 1993 for £270. 60 000 of the 70 000 Mega CDs shipped to Europe were sold by August 1993. The Australian release for the Mega CD was 19th April 1993.
The Mega CD (or Sega CD in America) came about just after when the Super NES was released and Sega was beginning to lose some sales on the Mega Drive/Genesis, so they released the Mega CD as an add-on to pick up sales and make sure they remained at the top of the market (By 1992 Sega had a 55% share in the US video game market). It was not the first CD-based video game system on the market, though. NEC had already released their PC Engine CD/Turbo CD/Turbo Duo, but was not very successful. The Mega CD/Sega CD was superior to NEC's system as well. Originally a CD tray unit that sat under the console, it was redesigned in 1993 as a top-loading unit that was smaller, cheaper (US$230), more reliable and would fit next to the Mega Drive II/Genesis II. Some European countries did not receive the Mega CD until this second version came out, thus the slow sales in the continent.