故事讲述了溺爱的妹妹去世的立花夏美和妹妹的未婚妻冬吾的爱情故事。在禁断之恋中摇摆不定的夏美、作为财阀名门子弟的冬吾、作为恐怖的幻影而现身的妹妹 · 春，本剧描绘的就是这样复杂的想法交织在一起的奇妙的三角关系。

在夏美最愛的妹妹春過世後，為了追尋妹妹的回憶，夏美提出與妹妹的未婚夫冬吾交往的條件『再帶我去你跟妹妹去過的地方』。在禁斷之戀中搖擺不定的姐姐、妹妹的未婚夫、作為恐怖的幻影而現身的妹妹，在複雜的糾結想法中所展開的奇妙三角關係的故事。

Natsumi's (Hikaru Takahashi) younger sister Haru passes away because a disease. She was just 19. Natsumi loved her younger sister a lot. Meanwhile, Haru was engaged to Togo. Togo comes from a distinguished family, who runs a large company. His parents care about pedigree a lot and suggests to Natsumi that she should now date Togo. Natsumi turns down their request, but Toho accepts his parents request to date Natsumi. Suddenly, Natsumi asks Togo to take her to places where he took her younger sister. Togo is surprised by her request, but he begins to take Natsumi around. Natsumi soon becomes attracted to Togo, but she feels a sense of guilt for her feelings.

最愛の妹を亡くした主人公が恋したのは、妹の婚約者だった！

いけない恋に揺れる姉、良家の名に囚われつつも足掻く男、幻影として姿を現す妹。

死んだ人間の想いまでが絡む壮絶で切ない三角関係のゆくえとは…？ 「お前が死んだら、俺も死ぬぞ」

今まで見たことがない「新しい形のラブストーリー」が誕生します！

세상의 전부였던 동생이 죽고 동생의 약혼자와 금단의 사랑을 하게 되면서 펼쳐지는 이야기를 그린 드라마