Guardians of the Light

A brief description of the manga Guardians of the Light:

2045 is a light year. a planet where the sea has severely encroached upon the shoreline. The sea monster known as “Suika” attacks a young man by the name of Yukari Fujikura as he is looking for his lost grandfather. His rescuer in this life-threatening predicament is the “Guardian of the Light,” who lives within a lighthouse and is the essence of light. Along with his superiors Sen Nakazawa and Akiko Douke, Yukari embarks on a tour around the lighthouses after joining the “Pilgrimage Agency,” a group that battles the Suika. The world’s future is what they are ultimately trying to rescue.