Well that's how trash pickup is done all across the country. Clear plastic bags (usually you have to purchase them specific to each ward and each trash type) on the footpath a few times a week. Usually gone by lunch time. Apartment buildings can end up with huge piles of them. The crows love picking apart the bags and spreading trash about.

Japan really isn't some mythical cleanly place and I've no idea how they managed to get that stereotype. I've seen fly tipping, piss jugs, trash along the motorways, riverbanks covered in empty drink bottles. Its the same as anywhere else.