Leonardo L. Vandimion is the eldest son of Duke Vandimion and the older brother of Scarlet El Vandimion in the series May I Ask for One Final Thing? He serves as the director of the Royal Secret Investigation Bureau and also acts as a subordinate, assistant, and attendant to Julius von Pallistan, the first prince of the Kingdom of Pallistan. He is a serious, earnest, and dutiful young noble who takes his responsibilities very seriously, often pushing himself to the point of physical strain. He genuinely loves his sister Scarlet and cares deeply about her well-being, but her frequent and violent escapades cause him considerable stress, leading to recurring stomach pains and a habit of carrying antacids. He is often seen quietly cleaning up the messes she leaves behind, working behind the scenes to manage the fallout from her actions. Leonardo possesses a clairvoyant magical ability known as the Eye of Truth, a gift blessed by the hunting goddess Hysteria, which allows him to see through deception and uncover hidden truths. This ability makes him highly effective in his role as head of the secret investigation bureau. He has medium-length black hair and gray eyes. Throughout the story, his role is primarily supportive, as he attempts to keep his sister's actions from causing too much political chaos while also managing his own duties. His development centers on his strained but loving relationship with Scarlet and his efforts to balance his familial loyalty with his official position.