Before dawn, small boats and larger fishing vessels equipped with bright gathering lights quietly gathered on the water. Red, blue, yellow, and green lights ripple across the river’s surface, evoking a constellation against the winter darkness. Glass eels measure about five centimeters long and are drawn from the sea into the river by the lights, then scooped up in nets. Known as “white diamonds” for their high market value, these tiny eels are a prized catch in Japan’s lucrative eel trade.