Ikegami Tsushinki is a Japanese manufacturer specializing in television equipment. In the mid-1980s, the corporation operated a video game division that assisted with the manufacturing and programming of various arcade games, including Donkey Kong. Though not credited, the company frequently left messages in the game's ROM data indicating their involvement.
History with the Mario franchise
Ikegami Tsukinshi had previously signed a contract with Nintendo for the programming and manufacturing of arcade games, Donkey Kong included. During its development, Shigeru Miyamoto would produce various ideas and characters that Ikegami would then program into the game.
The contract gave Ikegami exclusive rights for manufacturing Donkey Kong arcade boards. Due to the unexpected demand for the game, Nintendo ignored the clause and produced arcade boards of its own.
Nintendo later hired a company named Iwasaki Engineering to reverse-engineer Donkey Kong's code in order to produce a sequel. Ikegami Tsushinki insisted that it had ownership of the Donkey Kong code and that Nintendo had violated several clauses of their contract. Nintendo, meanwhile, insisted that it owned the code and filed an injunction against Ikegami Tsushinki in June 1983. In response, Ikegami filed a lawsuit for damages relating to Donkey Kong and Donkey Kong Jr. The case lasted until 1990, when a court ruling decided that Nintendo did not own the arcade Donkey Kong code. The two companies settled out of court. Despite this, a port of the arcade version of Donkey Kong can be found in Donkey Kong 64's Frantic Factory level and the arcade version would ultimately see a standalone release as part of the Arcade Archives line in 2018.