Surrealism, idiosyncratic symbolism, nostalgia. Blogs, toys, paintings, prints. The guy’s pretty much inventing a culture around his work.
I’m sure psychologist have calculated historical/ontogenetic timelines of what will be considered nostalgic in any given person’s lifetime. I figure once early childhood elements have percolated through a decade of nightmares, you pretty much have a lifetime bag of stuff to make you sigh and cringe. In Yosuke Ueno’s case, early anime and video games are now ready to serve on the surrealist canvas.