Bijin no Ane ga Iyagattanode, dou Mitemo Sugata ga Shiro no Jiki Hakushaku ni Totsugimashita Tokoro

Synopsis

What if I, a socially awkward girl, were to marry in place of my beautiful sister? Would I find a happy marriage with the perfect husband?! Mimosa, the daughter of the Norton family, is constantly compared to her sociable sister and spends her time at home reading and embroidering. The man her beautiful sister forces on her is clearly a white-collared... overweight man. When she marries the next Earl, for some reason, she's warmly welcomed...!? A timid love story between a timid young lady and a pure-hearted knight! (Source: Square Enix, translated)