/jp/ - Otaku Culture

That sounds pretty fucking gross, my dude.

I'm pretty sure salty or savory fillings are the staple of onigiri, you couldn't use vinegar or seaweed that way. Need pickled food or fish.

Vinegar goes good with rice because it can cover the whole rice grain. If you are going to make something sweet with rice, I would recommend making a mochi with coarse rice flour, domyojiko. These are legitimately flavored with strawberry, sometimes real ones, so they are probably the next evolution of your "sweet onigiri." Your idea would just be coming halfway, while sweet mochi makes it actually edible.