Japanese title as: 工藤新一への挑戦状~さよならまでの序章~. This is my story adaptation of the first Detective Conan live action special of the same name. This story mixed up with the part of the special's, The Great Detective Turned Small, plot including two first episodes' plots but there are few changes in this story. The half of a story begins with the high school detective who narrates this story had given a challenge letter by someone who have grudges against him and trying to solve the case on their schooltrip, following to the next half that leads to his transformation into a child which the main storyline began.
Disclaimer: I do not own Detective Conan