Narumi Katou has Zonapha syndrome, a condition that stops him breathing unless he makes someone laugh, which is how a drifting kung fu fighter ends up guarding Masaru Saiga, a wealthy boy marked for death by assassins wielding living puppets. Shirogane, a silver-haired woman sent from France to protect Masaru, joins them, wielding her own puppet Harlequin against attackers tied to a centuries-old feud between automatons and the people who first built them. As Narumi is pulled deeper into Masaru's world, the manga splits to follow both his fight against the puppeteers and Masaru's attempt to live an ordinary life inside a traveling circus.