Smartphone apps are used by everyone worldwide. However, unbeknownst to most, within these apps, there are creatures known as "Appmon" or "Appli Monsters." These AI life forms possess the ability to think and act, exist in the boundary between the digital space and the human world, allowing for effective interfacing and functioning of the two. Unfortunately, the "last boss AI," Leviathan, has taken over the Appmon with a virus and has started hacking every system, ultimately aiming to rule the human world through the net.
In the face of this daunting challenge, our protagonist, Haru Shinkai, acquires the Appli Drive and summons Gacchimon, a search app monster. As Haru delves deeper into this newfound world, he uncovers the hidden secret within the Appli Drive and becomes curious about the mysterious field located between the Appmon's existence and the real world. While exploring further, he discovers the "App Combine," the method utilized to merge two Appmons. As he progresses, Haru becomes increasingly determined to uncover Leviathan's true goal.
