To avoid the immense societal pressure of winning a four billion yen lottery, Kazura Shino flees to his father's secluded mountain dwelling. The lavish house amazes him, and he takes a tour, stumbling upon a secret corridor wider than the entire structure. Kazura follows it and discovers a village called Grisea that belongs to a different world. This town suffers from utter impoverishment caused by the catastrophic results of a recent war. As he empathizes with the people, Kazura decides to use his newfound wealth to provide them with food, medicine, and help improve their infrastructure, causing the town to prosper.
However, his arrival triggers an ancient legend about Greysior, a benevolent harvest god who disappeared after helping the village. Kazura's entry into this realm bears a striking resemblance to Greysior's tale. The Grisea villagers believe their god has "returned," and it won't be long before their neighbors learn of Kazura's presence and request his aid.
