In Ueno, Tokyo reside three young girls who go by the name of the Colors. Though they do not have an official duty to protect their city, they engage in imaginative games and perform virtuous deeds that benefit their community. The trio comprises Yui Akamatsu, Sacchan, and Kotoha, representing shyness, noisiness, and a love for video games, respectively. Guiding them is their mentor, Daigorou "Pops" Kujiraoka, who equips them with the necessary tools from his shop. Unfortunately, not everyone in Ueno appreciates the Colors' deeds. The local police officer, Saitou, often falls victim to their mischief to his dismay. However, despite finding their games tedious, Saitou assists them when possible. Although not officially recognized as protectors of the city, the Colors' presence brings happiness to those around them.