A minute or two of newly shot mobile phone video captures an elderly man repeatedly and, it seems, deliberately, preventing the door of a packed Nagoya commuter train from closing. It has, of course, gone viral.

The footage, co-starring flustered station staff and passengers at the end of their tethers, is exquisite theatre. Nine times, the train’s steel doors bid for closure. Nine times they are thwarted by aged flesh and mischief. The seconds tick by; the natural order of things is challenged; Japan’s famed punctuality is punctured.

The incident and its background are unimportant. But what stands out is the belligerent conclusion the video’s online audience quickly reached. This was, the masses decided, yet another case of rougai — the harm inflicted on Japan by its elderly.