Ep. 21: Senku mechanizes iron production and develops light bulbs using tungsten for winter preparations.

21

With electricity available, Senku automates ironmaking, allowing villagers to prepare for winter. Senku, Chrome, and Kaseki create light bulbs to celebrate Christmas by decorating a tree. Chrome explores caves with the new lights, discovering new minerals. Senku and Kaseki struggle to find a heat-resistant filament for vacuum tubes. During a New Year's sunrise, Senku gains inspiration from Suika, identifying tungsten as the solution. He then organizes a spelunking expedition with Chrome and Magma to secure the necessary materials for their scientific advancements.