It was probably more to do with the tax hike.
The typhoon only got here on the 12th, so it would've only affected 1 day of the week, and only in the Toyko area. The previous week felt the effects of the hike, but also would have included the last 2 days of the previous tax rate, with everybody panic shopping before tax went up, so we're only really seeing the full effect of it in this week.
On Era multiple users mentioned how stores were closed over the weekend, when most sales occur, due to the typhoon. It definitely had a major affect on sales.
When the herd loses its way, the shepard must kill the bull that leads them astray.