Ansatsuken (暗殺拳? lit. "Assassination Fist") is a Japanese linguistic neologism used to describe the assassination arts, which consist of any martial art developed with the intention of slaying an opponent.
In the Street Fighter universe, the term has been used to describe the martial arts used by Akuma (Gouki in Japan), as well as Gen's. The term Satsujinken (殺人拳? lit. "Murderous Fist") is synonymous with Ansatsuken, and the two terms are used interchangeably.
Ansatsuken and ShotokanEdit
The fighting style used by Ryu, Ken, and Gouken is listed in their Japanese Street Fighter IV: Master's Guide bios as a "martial art rooted as an art of assassination" (暗殺拳をルーツとした格闘術 Ansatsuken o rūtsu toshita kakutō jutsu?); Capcom USA originally referred to Ryu's fighting style as "Shotokan", despite bearing little resemblance to the real-life discipline. Because of this, Ryu and other characters who use similar styles (such as Ken and Akuma) are still called "shoto-clones" or "shotos" by fans.
The martial art styles used by Gen are known as the assassin arts of the Mourning Style (暗殺拳・喪流 Ansatsuken Sō Ryū?) and the Hateful Style (暗殺拳・忌流 Ansatsuken Ki Ryū?); both are personal styles which Gen developed based on his training in various Chinese kung-fu martial arts. They are more commonly known as the Mantis and Crane styles, respectively.