As a young detective, you work as an assistant for the famous investigator Utsugi. Your first important assignment is to investigate a murder case. A girl named Yoko was found murdered near a central bridge. During the investigation, you discover a strange rumor about a mysterious ghost-like "girl who stands at the back", spread around the school Yoko studied at. Soon, the young detective realizes that the case grows more and more complex and that he will need all his wit and talents to find the criminal.
This adventure game is dedicated entirely to investigation. You have a menu with various choices (Talk, Investigate, Think), as well as multiple topics to ask the suspects about. You should find clues by questioning people and gathering information, but also by examining areas - in certain places you should move a hand-like cursor over the screen and click on a precise spot to examine it.