This is the "Oshiri Tantei" series, starting with the first book, "The Case of the Curry," and including volumes 1 through 10 of the subsequent series. These picture books are popular with children due to their colorful covers. - Series Title: Oshiri Tantei (Butt Detective) - Author: Troll - Number of Volumes: Complete set of 12 volumes - Features: Colorful cover design - Content: Children's picture books There is some general wear and tear throughout. Volume 1 has a torn cover. Volume 2 is missing its cover. The inside pages are clean with no writing. Thank you for looking.