Lucia's guardian who serves as her guide. Hippo accompanies Lucia in her search for her pink pearl, and is among those who voice disapproval of her relationship with Kaito. He is also polite, always putting -さん, -san after every name, even when angry. In the anime, he is shown as Lucia's pet penguin. Later on, he is able to transform into a very cute human boy, as well as a creature called Hippocampus.

He later falls in love with Yuri. And Yuri also loves his human form.