I've played off and on for a couple of years, but I have never seen this run- it was always listed as 'coming soon".
I checked the first 15 pages of the forum, but didn't see anything about it either. It was not even mentioned when people were listing favorite/least favorite events.
I DID see the thread where the Japanese DMM version of Pero Pero was canceled back in August of 2016.

So, my question-
Is this an actual event? And if so, how does/did it work?

At this point I would say it will probably never happen and I would just ignore it.