When F.O.E designed this subclass for the Yamato server, it was meant to be introduced in a collaboration with a real-world idol group. However, during development, the group underwent a scandal and so the collaboration was ditched last-minute, forcing them to push out a half-baked subclass.
As a result, very few People of the Earth are found with the Idol subclass since it would be hard to explain the hows and whys of their existence; the ones who do have it are said to have hailed from, or been to, a foreign land.
Even among Adventurers, who can make some more use out of the subclass, the subclass is not very popular. Because a rather significant portion of its content was cut out, the subclass mostly just gives sparkles and hearts as a visual effect.