, stylized as ChäoS;HEAd, is a Japanese visual novel developed by 5pb. and Nitroplus that was released on April 25, 2008 for Windows. A port of the game, named , for the Xbox 360 console was released on February 26, 2009 followed by releases on the PlayStation Portable, iOS, Android, PlayStation 3 & PlayStation Vita. The game is the first in 5pb.'s Science Adventure series, and is described by the development team as a . The game's premise revolves around a high school student named Takumi Nishijo who unknowingly walks into the scene of a gruesome murder on his way home. More mysterious events start happening afterwards as more gruesome murders occur in the area. Takumi struggles to cope with reality and the delusions he experiences as he tries to avoid getting caught by the perpetrator behind the chain of murders. Although no release outside Japan is planned, an unofficial English fan translation has been released.