"Okitegami Kyôko no Bibôroku" is a mystery-romance series that has an interesting central concept, but poor execution and a middling second part where the concept runs out of steam.
The idea is basic. Kyouko is a very special detective: her memory resets every day, so she only takes cases she can solve in that period of time. In her cases, she constantly runs into Yakusuke, a young man with bad luck who seems to be the suspect in every case. Little by little Yakusuke falls in love with her, and will try to do anything to become her friend, even though she doesn't remember anything about him.
The first episodes of the series are quite charming, and the two central characters have chemistry (the show doesn't ask for high acting, so both of them can overact a little bit without problems). But on the second half, the series runs out of ideas, and it all becomes Yakusuke trying to get Kyouko's attention and heart, with uninteresting cases thrown into the fold. It all becomes quite repetitive. The central mystery, what happened to her before her condition, is also all over the place, and the show has little focus.
The mysteries are never especially "mysterious", but become less and less interesting as the show progresses. And the romance is also not very convincing and would have been better if it had been left out altogether.
In the end, an OK series, but not much more.