Coming from the foggy-yet-posh city of San Francisco, brunch to me is simply a fact of life. There was never a lack of options to choose from when it came to satisfying my innate city-boy urge to spend above-average prices in order to have what is essentially a late breakfast.
Even on my least-inspired days in the city, I could begrudgingly go to an IHOP or Denny's with friends and lament over the money we'd saved by patronizing an eatery devoid of a selection of ostentatious French dishes.
Given that San Francisco is arguably a drop in the bucket in terms of size and population compared to Tokyo, I didn't give so much as a second thought to whether or not brunch would be popular, or even available, when I moved here.