Sunsoft
From Sega Retro
Sunsoft (サンソフト) is a Japanese video game development company founded on April 16, 1971 as a division of Sun Corporation, itself a division of Sun Electronics. They have been responsible for developing and publishing numerous games since 1978, including several Sega licensed games. Interestingly they were also responsible for porting several Sega games to the Nintendo Entertainment System in Japan.
For reasons unknown, all Japanese Sega Mega Drive games published by Sunsoft had their covers printed backwards, the front being on the left of the spine, rather than the right.