Gangi-Kozou

がんぎ小僧

Gangi-Kozou (roughly "Jagged Boy" or "Chompers Boy") is a species of aquatic youkai similar to the Kappa. He's often depicted as a single youkai, though groups of them have been shown. He serves as an ally of Kitarō and his friends in various different adaptations. (Source: GeGeGe no Kitarou Wiki)