A scan of Donkey Kong's ROM proves to have a more revealing message than most:
CONGRATULATION !IF YOU ANALYSE DIFFICULT THIS PROGRAM,WE WOULD TEACH YOU.*****TEL.TOKYO-JAPAN 044(244)2151 EXTENTION 304 SYSTEM DESIGN IKEGAMI CO.
Ikegami Co. Ltd., also known as Ikegami Tsushinki, is an engineering firm still operating today, and seldom associated with video game development.
But back in the late 1970s and early 1980s, it was one of the first "shadow developers" in the Japanese market -- contractors like the famous TOSE
that would develop games silently, without credit.