Calt lives on Rat Island, a remote island on the edge of the world, a place where time seems to flow more slowly and "leisurely". He was forced to live in poverty, but he was surrounded by the love of his beloved family. Calt's father worked as a priest in the village, sharing God's guidance with the people in a small church. A monthly mass was being held at the church on that day as well.
Suddenly, however, misfortune struck: a massive earthquake hit Rat Island with a loud bang, completely destroying most of the houses. The misfortune continued when the earthquake triggered a tsunami that washed away the entire village. Not even the church was safe, as many people were drowned by the tsunami. Calt's father risked everything to save a girl from being drowned by the tsunami, but he too fell victim to it.
The nightmare passed, and the island regained its tranquility as if nothing had happened.
However, with the village in ruins and the disaster claiming so many victims, the villagers abandoned their lives on the island and left.
Ruruho, the girl saved by Calt's father, was left without anywhere to go, so the two of them remained on the island and worked together to make a life for themselves. However, the land is so salty that hardly any crops can be grown. Feeling that he cannot protect Ruruho's life, Calt decides to leave her alone on the island and go to the trading town of Belfald to work.
[translated from DLSite]