One summer day, university student Eihiko Morijo visits Suzuri, who lives in an old house in northern Kanto, to consult about an incident that occurred at a girls' gathering. Through Suzuri's investigative insight and conversations with Eihiko, the truths behind murders in Osaka and at a Western-style villa in Yamanashi are uncovered in this mystery novel.

One summer day, university student Eihiko Morijo visits Suzuri, who lives in an old house in northern Kanto, to consult about an incident that occurred at a girls' gathering.