I feel that this was a pretty good mystery romance. There's something about a time-travelling ghost that got me excited, and I'm glad the manga was enjoyable.
Yamano is a simple but fun character that was great as the MC. He is smart but not too smart, leaving the mystery open and letting readers feel smart at times. Saki/Tanigawa works well as the FMC, and she does a decent job of not being overly flat as the romantic interest. Having a living and nonliving version of the same character is actually pretty fun! The other characters are pretty simple, but the mysterious tone of each character keeps them interesting enough, even after their entire personality is revealed.
While normally I like focusing on characters, the mysterious story is the more interesting part here. It's well done and isn't completely obvious at the very beginning. I'm one to general know the basic plotline of an anime or manga fairly early, but this one took a bit more to uncover entirely. At the same time, there are moments where the writing has to be pretty frustrating to keep some things secret either to the reader or the MCs. Chapter 24 was the biggest issue I had with this. The time travel stuff I'm a bit mixed on, as it makes a story complicated, but it works here. The conclusion is overall satisfying as well, which is a nice change of pace compared to the many axed series I've found lately.
8/10 I recommend this as a good read for a mystery story. The story is fun and overall well paced, and the characters aren't overly frustrating. While I'm not sure if it'd be a good reread, the journey was one worth taking.