Hologrojband was invented by Kin. They were intended to trick people into thinking that they were the ghosts of Grojband who were rumored to be dead at the time. Kin programmed Holo-Corey to say: "Are you ready to rock? We'll see you in the park." so that they could make people come to see them play in concert.
They were programmed to go around town advertising Grojband's great return from the dead performance at the park but they somehow managed to break loose from their controls and have minds of their owns. Kon tried to stop them but only managed to get himself brutally beaten by Holo-Corey. At the park, Grojband put themselves inside of the bodies of Hologrojband and they played the song "I'm Back" at the park.
After they finished, they turned off the holograms and revealed their true selves and passed it off as a resurrection. The fans however believed that they were a copy-cat band of Grojband, but nonetheless still loved them. Later Kin reprogrammed Holo-Corey so that he could say more quotes, after that Grojband became a lot more fond of Hologrojband and they hung out in the garage with them.