Guardians of the Light is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

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…