The N-I or N-1 was a derivative of the American Thor-Delta rocket, produced under licence in Japan. It used a Thor-ELT first stage, a Mitsubishi Heavy Industries-designed LE-3 engine was used as a second stage, and three Castor SRMs. Seven were launched between 1975 and 1982, before it was replaced by the N-II.
Mitsubishi Heavy Industries, Ltd. is a Japanese multinational engineering, electrical equipment and electronics company headquartered in Tokyo, Japan. MHI is one of the core companies of the Mitsubishi Group. MHI's products include aerospace components, air conditioners, aircraft, automotive components, forklift trucks, hydraulic equipment, machine tools, missiles, power generation equipment, printing machines, ships and space launch vehicles. Through its defense-related activities, it is the world's 23rd-largest defense contractor measured by 2011 defense revenues and the largest based in Japan.