Nobunaga Concerto follows Saburo, a modern-day high school student who is physically unremarkable and lacks any interest in history. His life takes a drastic turn when he accidentally time-travels to the Sengoku period of Japan. Upon arrival, he encounters the real Oda Nobunaga, who is physically identical to him but physically frail and exhausted by the political machinations of his era. Nobunaga asks Saburo to take his place as the daimyo, leaving Saburo to navigate the treacherous waters of 16th-century warfare and politics. As Saburo attempts to unify Japan using his modern knowledge and unique perspective, he must maintain the facade of a ruthless warlord while struggling to uphold his own moral compass. The series explores themes of identity, the weight of leadership, and the butterfly effect of changing history, as Saburo interacts with legendary historical figures while trying to survive in a world where betrayal is the norm.