The game originally began as a smaller interactive Google Doodle game to celebrate the 2020 Summer Olympics and Paralympics in Tokyo, but after the events were delayed to 2021, Google were effectively given another year to expand it into a full-fledged video game with at least two and a half hours of content. This made it the largest interactive Google Doodle produced in the company's history. Their engineers were surprised at the large amount of side quests and dialogue they were able to fit into the game, but they struggled to get the game to run on mobile phones, tablets and desktop computers as it needed to be displayed on Google's front page. They managed to get the game to remember save data by saving it to users' local storage, so the game could be continued at any time. It is not fully known what the game's technological specs are, but the level design and sprite animations were created by Google in Adobe Animate, while the animated cutscenes were created by Japanese animation studio Studio 4°C in Toon Boom Harmony and Adobe After Effects.

Google collaborated with Japanese animation studio Studio 4°C to make the game, because they wanted its artwork and character designs to be done by Japanese artists. The studio started by researching folk tales and designing characters to appeal to audiences of all ages. While the main game was inspired by 16-bit JRPGs, the seven sports minigames Google proposed were inspired by other game genres including shooting gallery, rhythm, and skateboarding games. To connect the champions to each sport, Studio 4°C settled on using historical and mythological figures who used items that complimented the sports. Google originally proposed a fox as the game's protagonist, but Studio 4°C rejected this due to the fox's reputation as a trickster archetype in Japanese culture, and they opted to design a cat named Lucky as a heroic figure instead. Lucky was made a female calico cat both to break away from depictions of women as "scary characters" in Japanese folklore, and because of the traditional prominence of calico cats in the country through items like Maneki-neko ("Beckoning cat") figurines.