- Main article: Ikegami Tsushinki
A company known worldwide for its TV cameras and other broadcast equipment, Ikegami Tsushinki (池上通信機株式会社) dabbled in arcade games in the early 1980s. One of those games was Donkey Kong, on which Ikegami did the programming. A legal battle with Nintendo over the source code came later. Ironically, Ikegami also worked on Sega's Donkey Kong-esque Congo Bongo.
- Main article: Iwasaki
aka Iwasaki Giken Kogyo, Iwasaki Electronics, Iwasaki Engineering
Kyoto-based Iwasaki (岩崎技研工業株式会社) was a contractor responsible for disassembling and reverse engineering the original Donkey Kong so that Nintendo could make Donkey Kong Junior, as Nintendo did not have the original source code. Iwasaki went on to program a number of early Famicom/NES games. Members of the company established Intelligent Systems.
Mario Co., Ltd. (株式会社マリオ) was a joint venture of Nintendo, Dentsu, and Dentsu subsidiary Dentsu Prox (51% Nintendo, 49% Dentsu and Dentsu Prox) established in April 1991 to market and develop games, though it seemed to act more like a producer or coordinator. Hiroshi Ikeda (池田宏) of Nintendo was the president.  
Games: Hello Kitty World (FC), Sanrio Carnival 2 (FC, GB)
- Main article: Pax Softnica
Pax Softnica (パックスソフトニカ株式会社; originally written "Pax Softonica") was a frequent contractor to Nintendo.
- Main article: SRD
SRD Co., Ltd. (株式会社SRD; Systems Research & Development) was established in January 1979 and is headed by Toshihiko Nakago. It has worked with Nintendo on many games over the past 30+ years. Its development office is located at Nintendo's headquarters in Kyoto.
- Main article: TEC
TEC Co., Ltd. (株式会社テック) was a joint venture of Nintendo and Intelligent Systems that developed games and tools. It was later merged into Intelligent Systems.