Komono Kizoku ga Sei ni Au you desu

Hachi is reincarnated into the lowest tier of the privileged class: a petty, villainous noble who possesses only a tiny fief and loves to lord over commoners. Deciding to make the most of his previous life's frugal nature, Hachi resolves to lead a quiet, inconspicuous life as a "modest, low-ranking noble." However, his hyper-frugal, "waste-not, want-not" mindset accidentally grants him extraordinary magical power and an incredibly convenient set of skills. While he remains completely oblivious to his own rule-breaking power, influential figures begin to recognize the raw talent he cannot seem to hide. Though he was perfectly content staying a small fry, he keeps accidentally climbing the ranks anyway. The curtain rises on a noble fantasy of unintentional success.