Speaking of "child-like," have you seen the art of Takashi Murakami? He is another popular contemporary Japanese artist. I guess it is not really done in a child-like manner, but instead it looks like very graphic images painted for pre-teens and then distorted. The work follows the "cuteness" aesthetic I wrote about earlier. The artist states that he is following a theory he created called "Superflat."
He explores ideas of commercialism (his images are on everything from mouse pads t0 Louis Vuitton bags), low art, anime, and sexualized imagery that I find very interesting. I saw some of his work a few years ago in Chicago.