Nagumo Shinya is a highly skilled assassin in the manga and anime series Sakamoto Days. He is a member of the Order, an elite group of assassins, and is known for his versatility and cunning in combat. Despite his youthful appearance and playful demeanor, Nagumo is extremely dangerous and resourceful. As a former colleague of Sakamoto, he has a complex relationship with the protagonist, sometimes acting as a rival and at other times as an ally, adding depth to the series' dynamic.