I was cycling in Japan for about 2 weeks, just a few weeks ago. I was also impressed in most places by how clean it was, not only in the cities, but more generally speaking about everywhere.
At some point though, I was cycling along the coast of Mie then Wakayama prefectures, and although the scenery and roads were clean, I had a glance just behind the ramp walk, and realized that behind the trees, in the bush next to the road were hundreds of garbage bags, litter of all sort, really anything, just lying below. There was such a contrast from what my eyes were seeing until, I was shocked.
In another town several kilometres after (I forgot which place exactly, must have been while cycling up towards Wakayama city), I passed next to a big commercial area on my right. On my left there was a small patch of forest then the sea and again, that forest contained many many plastic bags, full but neatly tied up, every couple of meters or so, for several hundreds of meters.
I originally thought the first thrashes I saw along the road in the country side where "mistakes", like things flying off the window or pushed by the wind from another place (although there was a lot of garbage anyway). But when I saw these tied up plastic bags, they weren't there by chance, really people throw these bags away on the forest right here. That made me a bit sad, especially since it broke the original image I got.
(And I haven't spoke about the beaches and seafront all along that peninsula; I wouldn't walk bare foot there).
Then I came home in Switzerland, looked up the small water stream close to my place, and realized it wasn't as neat as one can see at first glance... So I should probably start with that before criticising other countries sigh