A young boy named Kai, who died from an illness in modern Japan, is reincarnated into a fantasy world. He is taken in by a priest of the Farley cult, the dominant religion, and raised alongside another orphan girl named Rukia, who becomes like a sister to him. In this world, the gods bestow unique abilities called blessings, marked by a holy seal. As Kai approaches his twelfth birthday, he uses his wits to discover his own blessing before the official ceremony, learning it is the Tenohira Village, a power granted by the god Aramira that allows him to access a special dimensional space. He dreams of using this ability to build a pioneering village and repay his adoptive father for his kindness.

However, his hopes are shattered at the blessing ceremony. When Kai reveals his holy seal, the church immediately labels him a heretic. The Farley cult considers Aramira an evil god, and those blessed by him are seen as threats. Kai is swiftly condemned and exiled to a remote, uninhabited island teeming with vicious monsters, a place meant to be a death sentence. While Rukia is not exiled with him, her fate becomes a driving force for his later actions.

Stranded and alone, Kai's survival hinges entirely on his cheat ability. The Tenohira Village is a unique space that only he can enter, and it grants him the power to summon items he was familiar with in his previous life. Using this ability, he begins to create tools, shelter, and a foothold on the deadly island. His lonely existence changes when he encounters Abyss, a mysterious synthetic girl living on the island. With her help, he not only survives but begins to thrive, establishing a small settlement.

As Kai develops his hidden village and tames the wilderness, news of his sanctuary spreads. Other outcasts and individuals who have lost their homes begin to arrive. His growing community includes a dwarf warrior born with a similar pioneering blessing, a fox-eared mage named Ren, and another girl blessed by Aramira named Kaede, who was thrown onto the island a year after Kai. Later, they are joined by Princess Yuri of a small country destroyed by war, along with her former aide, Sara. United by their displacement, this diverse group joins Kai, and their simple goal of survival evolves into a larger ambition: to build a new nation from scratch on the island.

The narrative follows their collective struggle to develop the island, manage resources, and defend themselves from monsters. A major turning point occurs when Kai and his friends finally succeed in rescuing his sister Rukia from the clutches of the temple that had imprisoned her. However, their victory is immediately complicated by a prophecy from a captured enemy priest, warning that the world will face destruction if nothing is done. With this new, grave threat on the horizon, Kai shifts his focus from mere survival to expanding his nation's power and influence. He prioritizes technological development and international trade, building harbors, aqueducts, lighthouses, and ships to establish contact with other countries, preparing for the calamity to come.