Shibuya Hikarie towers over Shibuya Station as night approaches Tokyo. Photo by Brett Homenick.
The person in question marveled at the missing Tokyu department store and made an assumption that the structure is being demolished as part of the train station's renovation.
In short: No. Not even close. The department store was replaced by Shibuya Hikarie, the skyscraper on the left side of the above photo. Tokyu finished it in 2012, and it's something that residents have been well aware of for years. There was even a Godzilla exhibit hosted there last year!
Could it be that some people still haven't heard of Google? Hm...