Masakazu Tanikawa (born 1980) was a Japanese youth who lived in Kabukicho, Tokyo during the 1980s. On the night of 12 December 1988, he and his playmates Yasunari Kanai and Michi Sonoda came across the dominatrix Ayu-chan and the ex-yakuza Kazuma Kiryu rehearsing an S&M scenario in a public park, and the children attempted to join their "game", unaware of what it was. After the adults insisted on ignoring the children and continuing the rehearsal, the children lost interest, said that adults were weird, and ran off to play somewhere else.