When feudal lord Itakura Katsuakira decides to prepare his samurai troops for the onslaught of modernization by having them compete in a marathon, his independent-minded daughter Yuki secretly joins the race.
After being neglected by her mother, a little girl is taken in by her uncle and his transgender girlfriend, who create a loving home for her.
The anime takes place on the screw-shaped island country of Nejigajima and follows the two "Bokyabots" Hebot and the Yurui Prince Nejiru as they collect different "Bokya Neji" screws. When the Bokyabots wear the Bokya Neji screws on their heads, they're able to compete in "Bokya Battles," battles for who can think up and tell the best jokes.
