From the official webpage for the event
The landmark Redbrick Warehouses in Yokohama (akarenga 赤レンガ) are running a number of Christmas events this holiday season, including the chance to meet Santa Claus.
On December 6th, 8th, 10th, 13th, 15th, 17th and 24th, Santa Claus will be taking a walk around the redbrick warehouses, both indoors and out. If you can find him, you can get your photo taken with him.
Other Christmas events at the Redbrick warehouses include a Christmas market, trick art Santa, Christmas wreath (and other) workshops, and Christmas fireworks (11th and 18th). For more information in Japanese: http://www.yokohama-akarenga.jp/christmas2015/