Although they are a bit hard to spot, I still managed to find several of these tiny bean weevils. Despite the name, these are not true weevils, which is obvious as they lack the rostrum (“nose”) of weevils. They used to be treated as a separate family (Bruchidae) but are now included in Chrysomelidae (leaf beetles).
Bean Weevil = chabara-mame-zoumushi
Location: In the valley below Mt. Yukawa in Munakata (google map)