An old blood vampire that sided with the humans to fight against the Kowloon children during the Kowloon Shock. Jirou was transformed into a vampire in 19th Century London. He used to be a lieutenant in the Imperial Japanese Navy until he was severely injured in a fight protecting Alice. Besides being an Old Blood, he also comes from a very special bloodline: the blood of the Sage. He wields a long katana which has a blade made of silver. During the war, after defeating most of the Kowloon children, he became known as the Silver Blade. He is weak against sunlight and water. He is shown being burned to the bones from staying into the ocean too long and releasing smoke under the sunlight, even though he was carrying an umbrella. He has a little brother, Kotarou, who is the only other vampire who shares his bloodline. He is considered to be the chosen Guardian.