Oga Tatsumi finds himself caught between two worlds when a baby demon named Beelzebub enters his life, forcing the delinquent into an unlikely partnership as a guardian. But when a mysterious portal opens to Japan's Bakumatsu period, Oga and Beel tumble backward in time, landing smack in the middle of the Shinsengumi's headquarters during the final days of the shogunate. Stranded in an era of samurai and political upheaval, Oga must navigate feudal customs while keeping Beel's demonic antics from unraveling history itself. The rough delinquent clashes with the honorable warriors at every turn, his modern street-fighting style and complete disregard for tradition making him either the Shinsengumi's greatest asset or their worst nightmare. These specials blend historical settings with supernatural chaos, mixing absurdist humor against the backdrop of actual historical events. The result is a comedic romp where nothing is sacred and the only constant is mayhem. Viewers looking for action grounded in joke-first energy will find their rhythm here.