Younger brother of Jiro Mochizuki, he does not seem to exhibit powers of a vampire, such as the " hide hand." although, he seems to have an extremely high pain tolerancy: as he is thrown into the ground and walls without injury in almost every episode. as commented by Mimiko Katsuragi, he not appear to be the brother of Jiro since he is not hurt by sunlight nor water, unlike Jiro. another fact is that they look totally different from each other: Jiro is tall, has black hair and brown eyes, while his brother is short, blond hair, and blue eyes. Kotaro staed that they are brothers because they are the last two remaining vampires of their special bloodline. they both carry goggles around their necks. he has the same speech pattern and bears a striking resemblance to Jiro's former lover, Alice. later, it is revealed that Kotaro Mochizuki is actually the reincarnaton of Alice.