Komono Kizoku ga Sei ni Au you desu

Reincarnated as the lowest rung of the noble ladder—a petty, villainous baron with a tiny territory and a habit of bullying commoners—Hachi decides to embrace his past life’s thrifty tendencies and live quietly as an unassuming, low-ranking lord. But his extreme "waste not, want not" philosophy unexpectedly awakens immense magical power and an array of remarkably useful abilities. Entirely unaware that he is breaking every rule of magic, Hachi continues to think of himself as ordinary, even as powerful figures take notice of his undeniable talent. Despite his earnest desire to remain a small fry, he keeps inadvertently rising through the ranks. Thus begins a noble fantasy of accidental ascension.