A fifth-year elementary student named Eiji Toomatsu, and his "inspiration" buddy, a dog named Pochirou. One day Eiji finds a mysterious book called the "Pikachin Research Book," and learns about the seven tools that make up the Pikachin Kit. Eiji presses a button inside the research book, and immediately a "Future Amazon" delivery arrives at his door with the kit. Eiji uses the blueprints included in the box to assemble the kit, but it seems as though 1% part of the kit is still missing.

In the franchise, the word "Pikachin" means the flash of inspiration or insight one gets about a new project, similar to the visual of a lightbulb turning on above one's head when someone has an idea. The concept of the franchise is "invention is 99% plastic models, 1% inspiration."