Ane no Migawari de Totsuida Nokorikasu Reijou desu ga, Shiawase Sugiru Fuhai Seikatsu wo Okurimasu

Magritte, the second daughter of Viscount Nefershall, has no magical powers and was raised as a servant by her talented older sister, who called her "leftovers." Even in this situation, the cheerful Magritte lives happily every day, fueled by her favorite cooking and memories of her past life. One day, she takes her sister's place when she runs away and is married to her sister's fiancé, Marquis Ganongoulf.

The Marquis is feared by everyone, rumored to wield the terrifying "corruption magic," but Magritte doesn't let this situation scare her. Instead, she seems genuinely excited to experience the Marquis's magic...!?

(Source: Kadokawa, translated)