Only Just Married (Konin Todoke ni Han wo Oshita dake desu ga) - Season 1, Episode 03: I fell for my husband who's in love with his sister-in-law
Trailer
Akiha enjoys her single life and she doesn't intend to marry at all. One day, she meets Shu for the first time. While they drink together, she tells him that she doesn't want to get married. Then, Shu Momose suddenly asks her to marry him.