In a fantasy world blending Western and Chinese cultures, Ageha, the only son of the Kikunoi Earl family of the Kiou Empire, was finished at the age of five. Besides his overweight figure, he had zero allies. Furthermore, it seems his suddenly appeared younger brother, Regulus, will kill him over the succession rights in the future. His only weapons are the memories of his past life as a Japanese person: cooking and sewing. However, Ageha ends up raising his brother. "My brother is super cute though?" Before he knows it, he's become a completely devoted older brother! For his chick of a brother, he makes educational toys, develops chawanmushi (steamed egg custard), and uses his past life skills to improve their neglected territory. The small steps of these young brothers' territory management fantasy involve gods and even change the country!