Hidomi Hibajiri is a dissilusioned young girl who never takes off her headphones. Her whole life consists of going to school, helping out at her mother’s cafe, and listening to music. And with nothing else to break the crippling monotony, she keeps her headphones on at all times. That is, until she is run over by a mysterious guitar-wielding woman. That same night, a robot barges into Hidomi’s room along with a boy from her class, Ko Ide, and the kids are chased around town together. They’re saved by the guitar-wielding woman from before, but now Hidomi’s got a horn growing from her forehead? Who knows where these robots are coming from, what kind of vespa woman this weird guitar woman is warning her about, or what this thing on her forehead is, but it doesn’t look like Hidomi is going to be able to ignore all this with headphones! [Written by MAL Rewrite]

Everyone in the world uses smartphone apps. But inside them lurks unknown creatures called “Appli Monsters,” or “Appmon.” The Appmon are AI lifeforms with the ability to think and act, and exist in the boundary between the human world and digital space. In the vast sea of the internet, the “last boss AI” Leviathan takes control of the Appmon with a virus and begins hacking every system, thus starting to control the human world from the world of the net. Haru Shinkai is led to acquire the Appli Drive, and uses it to materialize Gatchmon, a search app monster. (Source: ANN)