Arzest

 is a Japanese video game developer founded by members of Artoon, shortly after the company went defunct. The current staff of Arzest consists of former Sega employee and president Yoji Ishii, as well as executive vice president Naoto Ohshima and vice president Yutaka Sugano, who were also from Sega.

Arzest worked on the built-in Nintendo 3DS software StreetPass Mii Plaza, adding new features including SpotPass support to Find Mii II (known as StreetPass Quest II outside North America), the StreetPass map, and Puzzle Swap. The company also developed the minigame Mii Trek (known as StreetPass Explorers outside North America), which was released as part of a software update on September 1, 2016.

Arzest also developed the Nintendo 3DS Yoshi game, Yoshi's New Island, and co-developed the 3DS version of Mario & Sonic at the Rio 2016 Olympic Games alongside Sega and Spike Chunsoft.

Arzest was also involved in developing the giant battles for Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.