If you look for a leaf among the hills you will notice they are scarce. The hills have no trees around them, so there are no leaves. The leaves are scarce here on the hills.
Still looking for a leaf, you determine that they are far too scarce to find here. Just before you give up, you discover a giant bowling (ぼう) ball. As you pick it up, another one comes thundering down the hill knocking over a tiny tree.