Wrong Time and Place for Orgy

On September 18th, 1931, Japanese army invaded China using a fabricated act of terrorism as an excuse.  Exactly 72 years later, 380 Japanese tourists were having a three-day orgy with 500 Chinese prostitutes in a Chinese hotel.

Intentional?  Is it even possible for all 380 Japanese tourists to not notice the date?  Are such orgies common in China?  I don't think so.