Dragon Saber was released in December 1990 in Japan.
As its aforementioned full title suggests, it's the sequel to Dragon Spirit, which was released 3 years earlier. The game's title was abbreviated by Namco as 'DO' to separate it from Dragon Spirit's abbreviation, 'DS'.
This game is known outside Japan as just "Dragon Saber
" (without the subtitle).
Soundtrack releases :
Dragon Saber / Namco Game Sound Express Volume 4 [Victor Entertainment - VICL-40014, 40015 - March 21, 1991]