Keiyaku Mamahaha na no ni Boukun ga Kahogo Sugiru

Transmigrated into a forgotten bride, and doomed to be executed the tyrant emperor on their wedding night, she plans to survive by playing the wallflower only to unexpectedly catch his eye and get married in a flash. Braced for death, she instead uncovers the emperor’s secret and finds herself in his protection. She sets out to tame the tyrant and dote on her adorable new stepdaughter… only to somehow realize she’s the one getting pampered. Thus, begins a heart-warming isekai found-family romance.

Original Webtoon