The story begins with Cedy, the twelve-year-old third son of Count Dantes, waking up to a pleasant morning in his luxurious room. His peaceful, uneventful life is shattered when a frantic butler announces the sudden death of his father in an accident. This tragedy marks the end of Cedy's sheltered existence. He is forced to leave his home and the familiar comforts of the Count's mansion.
Following his father's funeral, Cedy is summoned by his eldest brother, Alexei, who has inherited the Count's title and estate. To Cedy's surprise, Alexei informs him that he will be granted a territory of his own: the island of Gandarsia. Despite Cedy's young age and lack of experience, Alexei believes he is capable of managing it, citing his good academic performance. Cedy is given only a day to prepare for his departure, leaving the familiar mansion with only a small suitcase and the bittersweet farewell of his former wet nurse, Mary.
On his way to the island, Cedy is unexpectedly offered a ride by his second brother, Paul, who is also heading to his own assigned territory. During their journey, Paul reveals that Gandarsia is not the idyllic island Cedy had imagined. To his shock, he learns that Gandarsia is an uninhabited island. This revelation, coupled with the stark reality of his new, isolated life, initially overwhelms Cedy.
Upon arriving at Gandarsia, Cedy finds a desolate, overgrown island. He discovers a dilapidated hut, which he recognizes from a childhood game called "Island Tsukuru." This realization triggers a flood of memories, revealing that Cedy has been reincarnated from modern-day Japan. He understands that Gandarsia is the setting of this game, and he possesses the ability to develop the island using a system of "points" and a "status screen." He immediately uses his points to restore a well, securing a vital source of fresh water.
The next day, Cedy's childhood friend, Eugenie, visits him on her griffon. Her arrival unlocks new possibilities, allowing Cedy to upgrade his hut into a small cottage using his points. He also learns about the game's mechanics, such as the importance of happiness for point recovery and the unlocking of new development options through social interaction.
Later, Cedy encounters Ruru, a young fisherwoman who has lost her home and boat due to her father's debts. Moved by her plight and recognizing a kindred spirit, Cedy uses his points to build a pier and a fishing hut for her, along with a new boat. This act of kindness further unlocks island development options. Ruru, grateful for his help, agrees to teach Cedy how to fish and handle a boat.
Together, Cedy and Ruru go fishing and catch a large sea bass and several horse mackerel. Cedy, drawing on his past life memories, demonstrates an unexpected aptitude for cooking, preparing a delicious meal for them. The next morning, Cedy's status screen shows an increase in his level and happiness, indicating progress in developing Gandarsia. He then uses his points to create a farm, planting turnip seeds, and plans a trip to the nearby town of Rubon to buy supplies. He invites Ruru to join him, as she wishes to sell her catch.