That’s right, if we consider the development history of mystery novels—or any genre of novels—as a long river, we will be surprised to find that this is not a straight river that runs all the way from the mountains to the sea. Instead, like the Amazon River, the rivers intersect and converge. A twist is a sub-type, and a tributary may be the beginning of the next type of prosperity. And Yasuhiko Nishizawa may be the author who cruises in the blurred and indistinguishable river at the junction of the two boundaries of reasoning and science fiction in a silver-white streamlined sub-ether-powered yacht.

In the novel, the author extradites two themes that are quite popular in science fiction—"multiple futures" and "time regression" into the mystery novels, and cleverly blends and transforms them into a high school student who will inexplicably repeat the same paragraph. Time nine times, and when he changes the variables, it may affect the future development.At the same time, if the grandfather of a high school student is murdered by an unknown person and reason, and that time can just be repeated, what to do to make the grandfather survive becomes an important issue for the protagonist.

Such a setting is not uncommon, and Philip Dick (Golden Man) has a similar performance, but relying on the intervention of science fiction settings, Nishizawa Yasuhiko has greatly expanded the "rationality" in reasoning novels The role of "reversal" has also become a word with another meaning.Perhaps it can be said that when Nishizawa Yasuhiko expanded the boundaries of mystery novels, at the same time, he kept his eyes on the center of mystery novels. Both subversive and conservative, this is Yasuhiko Nishizawa.