ローラーゲーム
Roller derby is a team sport played on roller skates on an oval track. Originally a trademarked product developed out of speed skating demonstrations, the sport underwent a revival in the early 2000s as a grass-roots-driven, five-a-side sport played mainly by women. Most roller derby leagues adopt the rules and guidelines set by the Women's Flat Track Derby Association or its open gender counterpart, Men's Roller Derby Association, but there are leagues that play on a banked track, as the sport was originally played from the 1930s.