The scratching?

I've noticed this happens in a lot of early Ozu, though it seemed even more common in this. I've wondered if it's Ozu reacting against the established taboos that made drama seem false. Pronounced scratching like that was probably something we weren't meant to see stage and film actors do. Ozu may have encouraged them to do it in order to create more realism by breaking that mild taboo. That's a complete guess though.