I’ve started walking to the train station from my house — a distance of about 5km — and part of the walk takes me through fields and along a country lane. Very pleasant! It’s still only early Spring so there are not so many insects around but there are plenty of these Knotweed Leaf Beetles, probably a good thing as they keep the Japanese Knotweed in check, which is why they might be used in other countries as a biological control agent for the weed.
Knotweed leaf beetle = itadori-hamushi
Location: Lane near Munakata Common (Google map)