Plot: Dragon Knight is an eroge/role-playing video game series by the game company ELF. There are four Dragon Knight games released between 1989 and 1997. There is also a hentai OVA series based on it, as well as some other media including audio CDs, novels and comic books. Wikipedia
Plot: Emerald Dragon is a role-playing video game developed by Glodia that was released for multiple platforms in Japan. It was released for NEC Corporation's PC-8801 and PC-9801 home computers on December 22, 1989, followed by conversions for the X68000, MSX2 and FM Towns. Wikipedia