Gosick

The Dark Reaper Finds the Golden Fairy (1x1)

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Kazuya Kujo is an exchange student from Japan. While exploring the library he encounters Victorique de Blois. While talking her extravagant brother Grevil arrives and questions Victorique through Kujo about a locked room murder. Victorique sets her mind to the task and comes up with an improbable but entirely logical answer.