One day, Kandume's can boy, who lived happily with his friends in the kitchen, becomes an empty can and is thrown away. Eventually, the can boy has a dream about the history of iron and humanity. Iron that melted and flowed out in a forest fire was discovered by humans when it had cooled and solidified. Iron transforms into knives and machines, and civilization develops... When the can boy wakes up, he is taken to a steelworks and reborn as a new steel material.