|Headquarters||1 Chome-4-10 Misonocho, Kodaira, Tokyo 187-0041, Japan|
|Website||Archive of official website|
Pier 21 (ピア２１, Pia 21) is an arcade in Kodaira, a city in the prefecture of Tokyo, Japan. It is famous for hosting The Masters, a regular Tetris The Grand Master tournament where the best players in the world gather to play.
On June 26, 2019, the business was sold and renamed to Retropia 22. While there were some changes in operation it still hosts The Masters.