Koei Tecmo Holdings Co., Ltd. is a Japanese video game, amusement and anime holding company created in 2009 by the merger of Koei and Tecmo. Koei Tecmo Holdings owns several companies, the biggest one of those being its flagship video game developer and publisher Koei Tecmo Games that was founded in 1978 as Koei.

Nobunaga's Ambition is a series of turn-based grand strategy role-playing simulation video games. The original game was one of the first in its genre, being released in March 1983 by the Japanese video game developer Koei. Nobunaga's Ambition takes place during the Sengoku period of feudal Japan. The player is tasked with achieving the ultimate goal of warlord Oda Nobunaga: the conquest and unification of Japan. Selecting Oda Nobunaga is optional, however, as the player is also able to choose from a variety of other regional daimyōs of the time.