Nintendo Treehouse is a product development division at Nintendo of America. While its main purpose is translating the games for the Americas into English, French and Spanish, they also help with QA Testing and product management. Starting in 2014, Nintendo Treehouse did a few livestreams including ones for the entirety of E3 2014 and the shows after.
The group was formed in the mid 1990s as an initiative to address the poor quality of the English localization of Nintendo games during the 8-bit and 16-bit era. The name originates from the localization of Donkey Kong Country where they "locked themselves away" in NOA headquarters while working on the game to keep the game's secrecy and the name held. As the decade progressed, many key members of joined the division, including Bill Trinen, Nate Bihldorff and Tim O'Leary.
Animal Crossing was a critical project for Treehouse as it was the first project where numerous things were changed to localize the game for a Western audience. They kept constant contact with the Japanese development staff.
In 2014, they started to have livestreams on Nintendo games on top of Nintendo Directs, due to the success of their E3 stream.