Even if titlescreen says 1990, Runark was released in January 1991 in Japan.
This game is known in US as "Growl
This game was dedicated to the late Mr. Katsujiro Fujimoto.
The game forbids the initials 'SEX' on the high score table. If you try, it gets changed to 'KOU'.
Pony Canyon / Scitron released a limited-edition soundtrack album for this game (Runark, Gun Frontier - PCCB-00060) on April 4, 1991.
Zuntata Records released a limited-edition soundtrack album for this game (Zuntata History L'ab-normal 1st - ZTTL-0038) on April 1, 1999.