I've not read much in this genre before, and this was a pleasant read that moved along at a rather quick pace... Once you make it through the first story that is. There are four stories in this book, which eventually are woven together but often subtly, which makes details very important while you read. However, the last three stories are so well-written and connected in comparison to the first, it leaves things a little lopsided and hard to get into given that the first foray isn't nearly as intriguing beyond the initial concepts. Something about the writing gets significantly better for stories two through four, and all four matter, but the initial story pacing, description, and writing just doesn't seem as well thought out as the rest. (Maybe something was lost in translation from Japanese to English possibly.) I still recommend this book as an interesting read with a very well defined time travel system with practical twists and solid character development.