- Jiro Mochizuki (望月 ジローMochizuki Jirō?) Voiced by: Takahiro Sakurai (Japanese), J. Michael Tatum (English)
- An Old Blood vampire that sided with the humans to fight against the Kowloon children during the Kowloon Shock. Jiro 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 and the Kin-killer. He is able to use some of the Kowloon powers as well as those of his own unique bloodline to be able to challenge even the Kowloon King and the three powers of the Special Zone.
- 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, Kotaro, who is the only other vampire who shares his bloodline. He is considered to be the chosen Guardian. As the chosen guardian, he is devoted to returning the sage's blood, which resides within him, into her reborn body, Kotaro. He reveals to Mimiko that once Kotaro fully matures and he gives back the sage's blood, he will no longer be around.
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