Sickness is a Visual Novel following the life of Suoh, a high school student turned violent criminal.
Following the deaths of his parents, Suoh is left without a home or source of income. All he has is his twin sister, Sara, who he promises to provide for, even if doing so means throwing his life away.
Using the entirety of their savings, the two move to another city, wherein Suoh quickly finds work. Sara commutes to her old school, Suoh works long, physically-demanding hours, and the two survive off instant food, barely scraping by. It isnt a happy life, but they make it work.
Or at least they did, until a violent outburst set into motion a rapid descent.