Tokyo Ghoul: "Jack"

The OVA serves as a prequel set 12 years before the main Tokyo Ghoul series. It provides a rare look into the high school days of the CCG's legendary, stoic "Reaper," Kishou Arima, before he became an unstoppable force, and introduces the backstory of Taishi Fura, a high school delinquent who eventually becomes a seasoned Ghoul Investigator.