We had stumbled upon a street closure by the Ginza Street Association. With a few temporary umbrellas adding to the “tactical urbanism” vibe, it felt very much to me like Park Ave in New York’s Summer Streets.
Wikipedia told me later “Each Saturday and Sunday, from 12:00 noon until 5:00 pm, the main street through Ginza is closed off to road traffic, allowing people to walk freely. This is called Hokōsha Tengoku (歩行者天国?) or Hokoten for short, literally meaning “pedestrian heaven”.