Tonari Totoro
I missed this trend, but found the mug, and bought it. Ebay searches didn't show any identical mugs, so it's probably a DIY project by a fan, who ordered it from a custom-printing business.
Once I had it, the Totoro world opened up to me, and I found the awesome DVD of films by Studio Ghibli, and a t-shirt.
The shirt isn't in the listing, yet, but I'll be washing it and adding it to the offer.