Edith is an orphaned girl who is treated coldly by her adoptive parents and sister. One day, her adoptive sister is offered a marriage proposal to Lionel, the eldest son of the Marquis of Granville, a very prestigious family. However, there is a reason for this proposal... so Edith becomes engaged to him instead of her sister. "I'm sorry, I can't believe you're engaged to me like this. Can you just bear with me for one year?" Her fiancé has only one year to live, but pure love brings about a miracle in this happy love story! 義父母と義姉に冷たい仕打ちを受けている天涯孤独の少女・エディス。 ある時、義姉に超名門・グランヴェル伯爵家の長男・ライオネルとの縁談が舞い込んできた。 しかしこの縁談は実は訳ありで…、急遽エディスが義姉の代わりに婚約することになった。 「ごめんね、こんな僕と婚約だなんて。一年だけ我慢してもらえる？」 婚約相手は余命一年、純愛が奇跡を起こす幸せラブストーリー！！