Sentoki 4 (戦闘機; fighter) is a 3D fighting game developed by S•T•K Project and published by ACS. It is the sequel to Sentoki 3 and the fourth installment of the Sentoki series. Released in 2009 for Arcades (ACS System 202: ENDYMION), PlayStation 3, and Xbox 360.
The game later recieved an update in 2010 in the form of Sentoki 4: Unleashed, which added new characters and stages, as well as rebalanced some characters and included new customization items. Released for Arcades (ACS System 202: ENDYMION), PlayStation 3, Xbox 360 and the PlayStation Vita (under the name Sentoki 4: Unleashed V+).
A final update named Sentoki 4: Final Edition was released exclusively for Arcades (ACS System 202: ENDYMION) in 2012, which added a balanced version of final boss K², as well as including new customization items and the ability to select stages from vanilla Sentoki 4. As Kei Ikushima reaches the finals of the Sentoki tournament, Ranzou Kihara, who was watching over the tournament, would unleash K-001, a clone created in Kei's image and infused with all of the fight data collected by Orion, upon her. After a grueling battle, Kei was able to defeat the clone and win the match, until Ranzou, not liking the results, decided to restart the match right there and then.
As the match got restarted, K-001 proceeded to attack the battered and exhausted Kei in cold blood, delivering vicious blows and strikes, which incapacitated her. She was about to be killed when Shin intervened and fought with the clone. He was eventually able to defeat K-001, but Kei barely survived after all of the injuries she suffered, and was sent to the hospital shortly afterwards.
Meanwhile, outside the arena, a mysterious man who goes by the name of "Nixon" watches the entireity of the tournament through some of the TVs displayed on a surplus window. All alone on the streets, Nixon has no memory about his past, living his current life as a vagrant, walking the streets of Tokyo aimlessly and occasionally fighting in underground pit fights as his only livelihood.
However, despite his amnesia, he seems to recognize the face of Ranzou Kihara. He dosen't understand it either. He just felt something... oddly familiar about him. It was as if Nixon's mind was drawn to this man, for reasons that aren't clear to himself at all. A rising urge builds up within him: a strong desire to meet Ranzou Kihara himself in order to make sense of his amnesiac mind.
Almost a year after the last tournament, Orion would eventually announce the fourth Sentoki: Global Martial Arts tournament. Upon hearing the news, Nixon wasted no time and decided to enter the tournament, his mind dead set on meeting Ranzou, thinking he has all the answers to his past.
