Golden Week

Golden Week was a Japan-exclusive event which took place between April through May, 2017, to celebrate Golden Week in Japan.

Announcement
The approximate translation for the event announcement was:  "During the period from Saturday, April 29 to Sunday, May 7, the petals will dance at PokéStops at about 2,500 domestic McDonald's, and the 'Lure module celebration event' will be held, so that you can catch a lot of Pokemon! GORuden Week goes to McDonald's GO!"