They just came out with all this "KITAROxATOM" stuff, featuring Ge Ge Ge No Kitaro (another classic manga character boy) and Astro. Two of my favorites!
Some other merch features Medama-Oyaji (Kitaro's eyeball father) with Higeoyaji
and Neko-Musume (Kitaro's demon catgirl friend) with Pinoco.
So, as a fan of both of these series/characters.... I have to say, this is obviously just a marketing ploy to sell more schtuff
A brilliant one, though - combine 2 character worlds that are both hugely cute, popular, and nostalgic and sell lots!
It worked for Who Framed Roger Rabbit - you've got to admit, the Donald-vs.-Daffy piano duel was one of the best things EVAR, as was the Mickey/Bugs parachute bit..... and this is the same reason Marvel vs. Capcom and Capcom vs. SNK sell so many video games ^_^