What is the name of the Koei Tecmo studio that co-developed Pokémon Pokopia?

Omega Force is the Koei Tecmo studio that co-developed Pokémon Pokopia.

Game Freak partnered with Omega Force to create the game. The partnership brought together Game Freak's experience with Pokémon and Omega Force's familiarity with sandbox and building-focused design. Omega Force is a development studio within Koei Tecmo, not a separate publisher.

The collaboration was recommended because Game Freak wanted support in a genre it had less experience with. Omega Force had previously worked on projects involving construction and world development, including Dragon Quest Builders 2.

Team Ninja is another Koei Tecmo development studio, which makes it a plausible but incorrect answer. It is associated with action-focused series such as Ninja Gaiden and Nioh, whereas Omega Force was the Koei Tecmo team credited on Pokopia.