Team Ninja's Yosuke Hayashi said that when they "were designing new features for Ninja Gaiden Sigma based on feedback from users, the number one request was - make Rachel playable!"[REF]
Regarding the process of turning Rachel into a playable character for Ninja Gaiden Sigma, Hayashi (who directed the game), stated: "As you know our goal with [Ryu] Hayabusa is to make the coolest action game character.