Samurai Warriors (戦国無双, Sengoku Musō; in Japan) is the first title in the series of hack and slash video games created by Koei's Omega Force team based closely around the Sengoku ("Warring States") period of Japanese history and is a sister series of the Dynasty Warriors series, released for the PlayStation 2 and Xbox in 2004. A port of this game called Samurai Warriors: State of War has been released for the PlayStation Portable, which includes additional multiplayer features.