An unconventional incest-themed event held at a rented ryokan in a famous hot spring town. An extremely surreal party where girls aged 8 to 12 gather completely naked, exchanging their children and indulging in one-night swaps. A gestalt-breaking group in which participants offer their own daughters in exchange for mating with someone else's daughter. The orgy ball held on-site was intensely perverted, and its scenes remain legendary to this day.