From Solving Queen Ophelia's Mysterious Death, in which the female protagonist comes back from the dead with just a few days to solve her own murder. It's got enough old timey locked room mystery novel vibes that it includes floor plans. But it also is a romance fantasy with isekai vibes, except in this case, the main character is reincarnated...as herself.
(What gives it a "reincarnated as" vibe specifically is that due to the character obtaining a posthumous perspective, she diverges radically from her previous self and also perceives all of her relationships differently.)