Light Calendar year 2045. A world where the coastline has been greatly submerged under the sea. A young man named Yukari Fujikura is attacked by the sea monster known as "Suika" on his quest to find his missing grandfather. In this life-threatening situation, his savior comes in the form of the embodiment of light, the "Guardian of the Light," who resides within a lighthouse. Joining the organization known as the "Pilgrimage Agency," an organization that fights against the Suika, Yukari sets out on a journey around the lighthouses alongside his superiors, Sen Nakazawa and Akiko Douke. Their ultimate goal is to save the future of the world