How do you beat phsyco mantis on Metal Gear Solid four ps3

You do not need to do anything to defeat Psycho Mantis in Metal Gear Solid 4: Guns of the Patriots on the PlayStation 3. He appears after you defeat Screaming Mantis and will only be present during the cutscene. During this time, you can press the cross button to view flashbacks when prompted, but the plot will advance itself. He will eventually be driven away by The Sorrow, who appears on the balcony and tells Old Snake that "the spirit of the warrior will always be with you".