In 2012, then Tokyo Governor Shintaro Ishihara said (in Japanese)
Westerners practicing judo resembles beasts fighting. Internationalized judo has lost its appeal.
In Brazil they put chocolate in norimaki, but I wouldn't call it sushi. Judo has gone the same way.
However, doing a search for "chocolate sushi", or even "chocolate sushi Brazil", doesn't seem to provide any info on sushi with chocolate in it being an established item, or at least a trend (akin to deep fried Mars bars in Scotland), in any location's cuisine, as opposed to it occurring only at a particular restaurant.
Is chocolate in sushi a thing, and if so, where can I eat it?