Orcas are huge and powerful. That's why they're called the Kings of the Sea. But not a lot is known about the habits of orcas in the waters off Hokkaido Prefecture's Shiretoko Peninsula. Here they gather in great numbers and engage in a puzzling display, arraying themselves in straight lines. Using drones, underwater sound equipment, satellite transmitters, and other tools, marine researchers and NHK undertake an in-depth investigation over 2 years. They learn that the nutrient-rich waters off the coast of Shiretoko make the area a magnet for orcas. And the key to their mysterious behavior might be found in their highly developed social intelligence and strong family ties.