Sachi-iro no One Room

That day, she was abducted. But to her, that abduction was a ray of hope -- the beginning of a new life. The girl promises to marry her abductor, and the abductor offers plenty of "happiness." This is the story of an abductor and his victim... How could it be so warm?

(Source: Crunchyroll)

Note: Chapter count includes one bonus chapter.