Preadolescent tarento (TV celebrities) tend to provoke my gag reflex. I can only tolerate preternatural cuteness if it's presented without irony or intensification. Ten-year-old Nozomi Ohashi, who's famous for singing the theme song to the animated movie "Ponyo," has, according to her Wikipedia entry, appeared in 16 television commercials so far this year, and none of the ones I've seen have sent me scrambling for the remote.
Eight-year-old Seishiro Kato, on the other hand, gives me the creeps, and he's 10 times more popular than Ohashi, initially owing to his appearance in the NHK yearlong historical drama "Tenchi-jin," but mainly to his role as kodomo tencho (child-store manager) in a popular series of Toyota commercials, where he plays the manager of a car dealership. Kato's sales pitches are smooth and professional, but the viewer is always reminded that he's just a child by things like his mother interrupting and telling him he won't get any dessert if he doesn't eat his vegetables.
Precociousness is built into the commercials. The ad people who came up with this campaign wanted a kid whose adorability would prevent viewers from switching channels or fast-forwarding through the break and, over time, create a buzz in the media. They were successful. Kodomo tencho is a star, so in the end it doesn't really matter what he says; and that's important to Toyota because what he "sells" is at least partly a fraud.