Ninja Gaiden Sigma 2 Plus has never been released for PC, so it has no PC system requirements. It came out on PS Vita. Released in 2013.
There is no emulator for PS Vita that this site will point you at.
Platforms: PS Vita.
System requirements for the game Ninja Gaiden II
System requirements for the game Yaiba: Ninja Gaiden Z
System requirements for the game NINJA GAIDEN Σ
System requirements for the game Ninja Gaiden 3
System requirements for the game Ninja Gaiden (1988)
System requirements for the game NINJA GAIDEN Σ2
System requirements for the game Ninja Gaiden III: The Ancient Ship of Doom (1991)
System requirements for the game Ninja Gaiden II: The Dark Sword of Chaos (1990)
