In the past, an orgy party involving 100 men and women was caught in Japan and the charges were acquitted.

There was a follow-up story, and the organizer was arrested, but it was ruled that it could not be punished because it was not prostitution, but a simple club meeting.

Roughly 100 men and 100 women were paired up to have sexual intercourse, and there were even records of such gatherings taking place like festivals during the Edo period in Japan.

To write an additional post, the money received as an attendance fee was not used as profits from prostitution, but was used to test participants for sexually transmitted diseases and purchase contraceptives, so it is not illegal.

For reference, they said they had an orgy without using a condom. It was really just a club.

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