100-nichigo ni Shinu Akuyaku Reijou wa Mainichi ga Totemo Tanoshii.１００日後に死ぬ悪役令嬢は毎日がとても楽しい。; Hyakunichigo ni Shinu Akuyaku Reijou wa Mainichi ga Totemo Tanoshii.; The Villainess Who Only Had 100 Days to Live Had Fun Every Day; The Villain Daughter Who Dies 100 Days Later Has a Lot of Fun Every Day.; The Villainess that Is About to Die in 100 Days Has Lots of Fun.

Lelouch, a duke's daughter, was pushed down a flight of stairs by someone and was transported to another space. There, she meets a "god-like being" who tells her that her fianc has been unfaithful to her and that she will die in 100 days. She knows that she can avoid the worst of it, but not escape death, and she begins to try her best to die beautifully in 100 days.