"We'll make the 20th century the age of electricity!"The protagonist, Kihachi Sakamoto, writes down his envisioned electrical inventions in the "20th Century Electrical Catalog," vowing to realize his dream with his admired older brother, Seiroku. However, Seiroku, who went off to war with the catalog, is killed in action, and the catalog goes missing.Time passes, and a shocking encounter with Inako Momokawa, the daughter of a sake brewer, sets Kihachi's stagnant life in motion again. Meanwhile, Yosuke Mitsuzoe, the heir to a steam-powered conglomerate who is also searching for the catalog, pressures Inako into a political marriage in exchange for a loan to the Momokawa family. Inako escapes Yosuke and reunites with Kihachi, and in her hands is the "20th Century Electrical Catalog," which was supposed to be lost
The missing "20th Century Electrical Catalog" reappears. Yosuke closes in on Kihachi, who doubts whether it's the real catalog, and Inako, who believes it is. Kihachi desperately resists with his homemade inventions, but is defeated by the power of steam, and Inako and the catalog fall into Yosuke's hands.Kihachi sneaks into the Hyakukawa house to find out the truth and learns that Inako is being forced into an unwanted marriage with Yosuke for the sake of the family. Kihachi rescues Inako, who has been locked in the storehouse, but is discovered by Yosuke, who chases after them. Will Kihachi and Inako be able to escape Yosuke, who is after the catalog?
Having captured Kihachi and Inako, Yosuke obtains the "20th Century Electric Catalog." However, the "secret" Yosuke seeks is not found within it. Although Yosuke denies it's a fake, Inako believes that Kihachi's dream and talent are genuine. A dejected Kihachi, by chance, discovers his brother Seiroku's feelings embedded within the catalog. A challenge for Kihachi and his friends, risking their dreams to oppose Yosuke, begins.
Inako meets a grieving shop owner whose loss echoes her own. Fully believing in Kihachi's skills, she asks him to build an electric machine to help.