Japan (日本, Nihon) is the home country of Koei Tecmo. It also tends to be the main setting for many of the company's titles, some of which do not get localized beyond Eastern Asia.
Koei Tecmo has focused on the following time periods of Japanese history with their numerous IPs:
- Ancient Japan - Mythological dates spanning within the era of creation.
- Heian Period - Spanning the years 900~1185.
- Warring States - Spanning the years 1500~1615.
- End of Tokugawa Regime - Spanning the years 1853~1869.
- World War II