Kuromukuro: Season 2 (Netflix)

A mysterious relic, known as the Black Relic dating back 450 years, is discovered in a dam. The United Nations Kurobe Research Institute is established in order to figure out the artifact's origin.

Scholars from all over the world gather at the Kurobe Research Institute. The scholars even bring along their children, who must study at the nearby Tateyama International High School. Among those students Yukina Shirahane, the daughter of the institute's director. When robots and machines (mecha) begin to attack the institute, Yukina, along her fellow students, pilots, and researchers must fight back with the help of a mysterious samurai.