Introduction
Chaos;Child (stylized as ChäoS;Child) is a 2014 visual novel video game developed by Mages. It is the fourth main entry in the Science Adventure series and a thematic sequel to Chaos;Head Noah. It was initially released for Xbox One, and later for PlayStation 3, PlayStation 4, PlayStation Vita, Microsoft Windows, iOS, Android, and Nintendo Switch. An English localization was released for the PlayStation 4 and PlayStation Vita by PQube in 2017, and for Windows and Switch by Spike Chunsoft in 2019.
Story
In 2015, six years after the New Generation serial killings and the Shibuya Earthquake, high schooler Takuru Miyashiro is searching for a story to cover for his school's newspaper club. After looking into the cases of two recent deaths, Takuru notices that the killings are mimicking the New Generation Killings from six years ago and are occurring on the same dates.
Despite the objections of his foster sister Nono Kurusu, Takuru and the rest of the newspaper club, including childhood friend Serika Onoe, Shinji Itou, and Hana Kazuki, begin to investigate the killings with the goal of exposing the culprit themselves. Along the way, Takuru meets characters such as Literature Club member Hinae Arimura, the cold and calculating Mio Kunosato, detective Shinjo Takeshi, and young Uki Yamazoe.
Mio reveals the existence of Gigalomaniacs, people who have the ability to manifest delusions into reality. After meeting with Hinae, who is also a Gigalomaniac, Mio and Hinae deduce that Takuru must be a gigalomanic with the ability of telekinesis.
Hinae and Takuru are attacked by a pyrokinetic Gigalomaniac, assumed to be Senri Minamisawa, an old friend of Nono's who presumably died in the earthquake. Takuru remembers back to his childhood, where he found Senri being experimented on while exploring the hospital. He assumes that Senri is upset that Takuru never stopped to help her, and is attacking him in revenge.
Shinji murders Takuru's younger foster sister Yui, claiming that he was in love with Senri and wanted to exact revenge on Takuru for abandoning her at the hospital. When Nono proves it was impossible for Shinji and Senri to have met in the past, Shinji has a mental breakdown and collapses.
Nono soon finds evidence to implicate Serika. She confronts Serika on the school rooftop, where they reveal themselves as Gigalomaniacs and fight each other. Takuru arrives shortly after, to witness Nono killed as a result of the fight. Takuru is officially implicated for the murders with the news widely spreading across Shibuya.
It is revealed that Serika was actually Takuru's imaginary friend, who he booted into reality when he awoke as a Gigalomaniac. Serika reveals she is working with Sakuma Wataru, Takuru's foster father, to orchestrate the killings.
Sakuma, who has rebuilt an artificial Gigalomaniac device from the wreckage of Noah II, fights with Takuru, revealing that his motivation was simply to have fun torturing and experimenting on Gigalomaniacs. Takuru wins the fight, killing Sakuma. Serika soon shows up and reveals that she was created with a purpose: to give Takuru something to do, and help him do it. As Takuru was a fan of the original New Generation killings, Serika orchestrated the copycat killings to have Takuru solve it, and become a hero in the process. Refusing to let his original wish play out, Takuru uses his powers to wipe Serika's memory and free her from his wish. Takuru is later arrested for the murders.
Character routes are unlocked, revealing Hinae's backstory of losing her brother in the earthquake, Kazuki's status as a Gigalomaniac, teacher and club advisor Wakui Shuuichi as a member of the Committee of 300, and Nono as the real Senri Minamisawa.
After the Character routes are completed, the True End is revealed. Serika wakes up three months later, with little memory of who she was before. She finds herself drawn to Shibuya, where she meets Mio, Shinjo, and Takuru. Mio introduces her to Chaos Child Syndrome, in which its affected are trapped in a synchronized delusion, causing rapid aging in the process. They travel to a facility underneath the school, where they free everyone from the syndrome.
Weeks later, Takuru is to be transferred to a prison. On his way out of the hospital, he encounters Serika. Passing each other, he and Serika both claim that they do not know each other, and they will live their lives apart.