Originally Posted by railroadtycoon

Actually that particular Starbucks (and most Starbucks in Tokyo) opens at 7am ish on Weekdays only. On weekend and holidays that store opens at 9am. You don't get a lot of commuters/workers on a weekend as you would on a weekday.

But as mentioned, commuting times, mode of transport and work times have a lot to do with it. Many folks are traveling in from the suburbs, a trip that takes 1-3 or more hours, typically leaving home around 6 or 7, arriving into at 8-10 am, makes sense for stores to be opening around those times for the large influx of commuters and peak business.