Lunar: Eternal Blue is a role-playing video game developed by Game Arts in association with Studio Alex for the Sega CD as the sequel to Lunar: The Silver Star. The game was originally released in December 1994 in Japan, and later in North America in September 1995 by Working Designs. Eternal Blue expanded the story and gameplay of its predecessor, and made more use of the Sega CD's hardware, including more detailed graphics, longer, more elaborate animated cutscenes, and more extensive use of voice acting. Critics were mostly pleased with the title, giving particular merit to the game's English translation and further expansion of the role-playing game genre in CD format.

Set one thousand years after the events of The Silver Star, the game follows the adventure of Hiro, a young explorer and adventurer who meets Lucia, visitor from the far-away Blue Star, becoming entangled in her mission to stop Zophar, an evil, all-powerful being, from destroying the world. During their journey across the world of Lunar, Hiro and Lucia are joined by an ever-expanding cast of supporting characters, including some from its predecessor. Eternal Blue was remade in 1998 as Lunar 2: Eternal Blue Complete, published by Kadokawa Shoten and Entertainment Software Publishing for the Sega Saturn and PlayStation, with the latter version localized and published in North America by Working Designs.