You’re playing Nishijou Takumi, a fully fledged otaku with no interest in the real world. He’s an Internet addict, a shut-in who attends his second year of high school just for the sake of keeping his attendance rate high enough. He lives alone in a small container house on top of some Shinjuku apartment building he calls the Base, away from his parents and his little sister. This goes without saying, his place is filled with piles of eroge packages, figures and other goods, empty convenience store lunch boxes etc. ダメ人間
At the time, Shinjuku is a stage to a series of murders named as The New Generation Frenzy (abbr. NewGene). Victims are young people who are murdered in very brutal ways. Takumi is a net addict, and the events surrounding these murders were covered by various news outlets, so naturally he got involved in Internet discussions about them. One day he starts chatting with this person nicknamed Shougun (将軍, tl. General) who has a huge take on the next NewGene murder. He posts links to Takumi that are filled with guro imagery of the next murder scene, he also tells him the way the victim got killed. Takumi’s search for the bizarre leads him straight to the mentioned murder scene, an event that disturbs his life of a hikikomori.