Agasa kurisutī kanzen kōryaku (アガサ・クリスティー完全攻略 = Agatha Christie - Complete Walkthrough) is a Japanese non-fiction reader's companion to Agatha Christie's works. First released in 2015, an updated edition was published in 2018 by Hayakwa Shobo. The author, Shimotsuki Aoi (霜月蒼) or Ao/Aoi Shimotsuki in Western format is a law graduate from Keio University, Tokyo and a mystery researcher and has written several other books on detective mysteries. The word "攻略" in the title also translates as "cheats". This word is often used in the context of articles/books about computer games which offer "cheats" or hints about how to play a game. In 2015, the book won the 68th Japan Mystery Writers Association Award (criticism and other categories) and the 15th Honkaku Mystery Award (criticism and research category). The cover of the book also bears the English title: "The Definitive Guide to Agatha Christie" but this is not a translation of the Japanese title.
The author had been a regular blogger and contributor of online reviews of mystery works. He wrote this book in response to his readers and friends who often asked him which Agatha Christie book should they read next or which book he would recommend. The book comprises detailed reviews of Agatha Christie's works (including those by Mary Westmacott). For each work, he discusses the plot and also his personal critique about the work's strengths and weaknesses. Each work is given his personal rating from 5 stars (best) to 1. Spoilers are avoided and printed separately at the end of the book.