Storyline
Four years before the events of Kansen 5, Makoto Nakazawa was caught in the devastating UNKNOWN-LV4 virus outbreak in the Tohoku region. He lost his family and friends and also suffered severe memory loss, leaving him unable to remember much of what happened during the disaster.
After several years in an institution, Makoto is taken in by Natsu Hyuga, a former member of the Self-Defense Forces who had rescued him during the outbreak. The two eventually move to Tokyo, where Makoto begins rebuilding his life while living with Natsu.
Although Makoto has returned to a peaceful school life, he remains troubled by the feeling that he cannot fully understand the loss he experienced. Four years after the original disaster, he joins his school's newspaper club and is assigned to cover a sports training camp on an island in the Seto Inland Sea.
Makoto travels with his close friend Fudebuchi and upperclassman Satsuki Minami. Akari Ochi, a younger student whom Makoto has secretly grown fond of, also joins the trip as a member of the cheerleading team.
What begins as an ordinary school trip quickly changes when signs of the UNKNOWN-LV4 disaster begin to appear once again. The group becomes caught in a new outbreak, forcing Makoto and the others to confront the same threat that destroyed his life four years earlier.
As the situation deteriorates, Makoto must struggle to survive while protecting the people around him. The different routes follow the characters' individual experiences during the outbreak, with choices leading to different events and endings.
The story expands on the previous Kansen games while bringing the series' central outbreak storyline to a new location, combining survival, character relationships, mystery, and branching visual-novel routes.