In the near future, an unexplained phenomenon has occurred on a distant island called The Lost Grounds, giving birth to a new species of humans. These evolved humans, called Alter Users, can manipulate matter and reform (or alter) it into unique forms. On this remote island, those born inside a walled city are citizens, while everyone born outside live lawless lives in the badlands. In an attempt to keep the peace the police force HOLD along with the elite alter-user squad HOLY capture dangerous native alter users and offer them a choice... join HOLY or be imprisoned. After young native alter user Kazuma's run-in with HOLY, questions arise. Is HOLY really interested in the good of all, or is there some other motive behind their actions?